Angry Birds: Part 1, Barbarism from Above


These familiar, feathered, fellow Earthlings are often the subject of much adoration from humans, and most birds that enter our daily lives occupy a place of fondness in our hearts. When we think of birds, we imagine, before essentially anything else, their beauty. They are revered across scores of cultures for their complicated and uplifting songs, a trait that exists as the result of meticulous tuning and retouching by sexual selection. Their wind-blown arias range from the simple, structured trill of the western meadowlark, to the complicated, crystal clear chimes of the white-rumped shama, to whatever the hell this insanity is from the superb lyrebird. Many are also regarded physically beautiful, and are gifted with soft elegance in flight, and their frequently vivid feather pigments make them among the most colorful vertebrates outside of a handful of coral reef fish and perhaps poison dart frogs. We equate grace, tranquility, and majesty with birds of varying flavors. Peace with the dove, might and prowess with hawks and eagles….

…the sensation of receiving a prostate exam from Dr. Cactus Fingers…with the potoo

I mean, shit, in Abrahamic and Zoroastrian faith traditions, we even envision angels, the shimmering middle-men of the Creator, as having bird wings plastered on their backs. Lots of things have wings and fly (bats, flies, beetles, and R. Kelly for example) but no, it was the bird’s weird, fluffy, elongated arms that were selected to be associated with a supernatural being that, supposedly, is a distilled amalgamation of all things right in the world.

We also appreciate some species of birds for their intelligence and affection, as well as their impressive capacity for vocal mimicry (I’m looking at you, parrots and mynahs). Many groups of birds are startlingly clever, and corvids (the family to which crows, ravens, rooks, and jays belong) are by-and-large tool-using, highly social, unnervingly observant braniacs that exhibit complex puzzle-solving abilities that make your “whip smart” border collie look like an insipid, drooling dipshit, and are more akin to a ruthless contingent of droogs than to tweety birds.

When we aren’t putting their image on national flags, making our clothing out of their feathers, or pasting them on random knick knacks, we are eating them. Birds are a common source of protein the world over, and here in the States, we appreciate poultry so damned much, that we’ve invented a way to shove as many species of fowl as possible up each other’s asses in order to make a delightful Russian nesting doll of bird flesh. We love the taste of birds so much that we’ve managed to slaughter many species permanently into the past tense. Passenger pigeons used to blacken the skies of North America until European immigrants came along and gave them the good ol’ ‘buffalo treatment’ and straight up blasted them out of their volant swarms with as much pause and contemplation as we give the flipping of a light switch. Humans hunted the flightless red rail of Mauritius to extinction by capitalizing on the birds’ affinity for red-colored objects by pulling out red cloths to lure the poor animals in close…and then bludgeoning them into shrieking oblivion with large sticks.

So, we historically have had sort of a “love/love-to-death” relationship with feathered fauna. It is then, perhaps, not surprising that birds, despite all their charm, can also be somewhat of a nuisance…as some sort of karmic retaliation, I’m sure. A great deal of this comes from their incredibly badass pedigree. It’s important to remember that birds are dinosaurs. Literally. Not kinda, halfway, tangentially related to dinosaurs. Nowadays, the paleontological evidence strongly suggests they ARE therapod dinosaurs, through and through. It’s not so much that Polly is descended directly from T-Rex, but goddamnit if they aren’t kissin’ cousins (a reality that is unavoidably observable in this experiment that aesthetically transforms a lowly chicken into a sickle-toed raptor with ease). Every innocently chittering and whistling thrush and sparrow outside your window is a representative of the last remaining groups of dinosaurs (a clade of critters known as the Maniraptorans), the only group to emerge out the other side of the mass extinction that marked the end of the Cretaceous.

Even after their bigger, toothier relatives kicked the bucket, birds sort of took up the mantel of filling the “giant, menacing, everything-runs-away-from-me monster” niche. In South America, they reigned for tens of millions of years over their ecosystem in the form of flightless, knife-faced homicidal maniacs the size of Shaquille O’Neal (something I wrote briefly about here). One group, the pelagornids, or ‘pseudo-tooth’ birds, went retro and evolved spiky projections from their beaks that basically functioned like teeth. Up until relatively recently in New Zealand, massive, Tolkienesque eagles hunted even larger flightless birds (moas), and likely plucked off the first colonizing Maori like modern hawks take down field mice.

So, given their evolutionary legacy, perhaps it isn’t so shocking that birds, given the right conditions, can be, well, downright unpleasant. I’m a lover of birds (if not solely for the fact that they are, as far as we can tell, motherfucking dinosaurs are you kidding me), but even I can admit that they can be obnoxiously loud (the relentless cooing of the ubiquitous zebra doves on the Hawaiian island I live on is beginning to be an unwelcome wake up call) and foul tempered. Anyone who has spent any time around roosters or overly “friendly” swans knows this. Even as pets they can reek something awful, and then there’s the whole issue of birds shitting as much as your average Royal Caribbean patron. Birds are notorious for spreading disease to people and other animals, and can be agricultural pests as introduced/alien species. But, I suppose that might not be enough horror to transform your conceptualization of birds into that of enraged, dead-eyed, screeching, spray defecating, reptilian nightmares. Especially if your most negative associations with birds just come from getting caught underneath a pigeon releasing its bowel ballast, or from a frustrating bird and pipe-themed app game, which shall go unnamed…

“Up! Up, you stupid piece of shit!”

We know that birds easily have the capacity for bouts of aggression, towards each other, towards other birds, towards their prey, and towards humans. A certain proportion of it is simply overtly aggressive mating; there’s a good chance that whatever “language” mating vocalizations of many species are in, it doesn’t have a word for ‘consent.’ An endangered species of parrot from New Zealand, the kakapo, can be sexually aggressive; and by sexually aggressive, I mean it will mount and dry hump the back of a human’s head. Male dabbling ducks are down-to-their-core gang rapists that possess a shudder-inducingly brobdingnagian, thorny, spring-loaded death dick that looks like it slinky-ed its way out of Tim Burton’s most Freudian, repressed nightmares.

The sins of these dinosaurian, deceptively innocent beings are common and diverse. Obviously, birds-of-prey like hawks, falcons, owls, and eagles are the tigers and wolves of the sky, and rain death upon fuzzy, soft-bodied mammals and clueless reptiles the world over. Vultures chase off other birds from carcasses. Cuckoos are brood parasites that pass off the child-rearing chore onto small, ill-equipped songbirds…which inevitably leads to the slow, pathetic malnourishment of every other chick in the parasitized nest. Corvids routinely bully other birds just for shits and giggles. Just recently, a crow and a seagull (basically, the avian equivalents of a pipe-wrench-wielding Mob leg-breaker)  batterfanged the bejesus out of two hapless doves released by the Pope…to, hilariously, symbolize peace.

You might be aware that the cassowary, a flightless bird closely related to emus, native to northern Australia and Papua New Guinea, has a reputation as a violent animal…prone to defending itself against perceived threats with a casual leaping, roundhouse kick, armed with a razor claw-tipped foot (a behavior that has injured many, and resulted in a single recorded death).

But, the face of badassatry and biker gang ethics in birds isn’t as narrow as bitey swans, prank pulling ravens, and the occasional murderous cassowary. Birds take after their deadly, extinct, dinosaur brethren in more ways than you’d expect, and the reverberations of eons past can be picked up in behavioral and physical attributes across a very wide diversity of these marvelous animals.

The stoic motherfucker above, the one with the icy, blue-eyed stare and unwavering resolve in the face of a snow storm, is the first entry on our list of unappreciated, cantankerous birds; the giant petrel.

While the giant petrel looks very much like a seagull that spent a little too much time reading A Song of Ice and Fire, it is actually a wholly different animal, and genetically and evolutionarily speaking, it belongs to a different taxonomic order of birds. Giant petrels are a part of the Procellariiformes, a group of birds that consists of the most charismatic and well-adapted (and, unfortunately, often times endangered) sea birds on the planet (albatross, shearwaters, petrels, fulmars, etc.). In contrast, gulls are nested within the Charadriiformes, which contains things like plovers, puffins, terns, and snipes (generally considered “shorebirds”). Perhaps predictably, a good rule of thumb to follow is if the bird you are looking at is comfortable being way, way out at sea for long periods of time (in a non-migratory context), it’s more likely to be within the Procellariiformes; if it is ubiquitous along shorelines and inland bodies of water, and not found on far-flung islands in the middle of ocean basins (perhaps with the exception of the tern family)…it’s probably a member of the Charadriiformes instead.

Many of the birds within the Procellariiformes have a tendency to spend an extensive amount of time either feeding or migrating over vast distances of open ocean. Most species are colonial breeders, preferentially seeking out remote islands that are relatively predator-free to nest in massive numbers, and as adults they return to the colonies in which they were hatched year after year for breeding season. While it is thought that navigation back to these colonies relies on astronomical cues, the need for locating nests within these large colonies, and for finding ample food during such long, isolated flights over thousands of miles of open ocean, still exists. The procellariiform solution is found in their exquisite sense of smell.
Procellariiform birds are commonly referred to, collectively, as “tubenoses”; a nickname that refers to the extension of the nasal passages found in this group, forming bony tube (of varying length) that runs along the top of the bill. This is basically like if you had an empty toilet paper roll taped to your nose…but, you know, less stupid looking. This tube likely assists in capturing small particles in the air, and enhances their sense of smell, allowing them to find far-away sources of food on the wing out in the ocean, and potentially their own nest within the congested hustle and bustle of a smelly, shit-encrusted seabird colony. That goofy looking shirt-sleeve nostril is actually their version of Google Maps and Urban Spoon.
Another adaptation to extended time out at sea is the capacity for tubenoses to drink seawater. Yes, these birds engage in a behavior that would surely sicken you or I (or even potentially kill us due to hypernatremia (too much salt in the blood)…to understand the magnitude of the dangerous effect of this condition consider what happens when you pour salt on a slug…that horrific shit is what happens to the hypernatremic brain). Tubenoses are aided by a second installment of evolutionarily-derived gizmos on a head that, apparently, is not that unlike Batman’s utility belt. Tubenoses have the ability to purge salt from the water they drink by use of specially adapted glands at the base of their bill, which, with the help of a number of other organs, re-route sodium chloride from the ingested water away from the blood, and into these glands. The glands then secrete a highly-concentrated salt solution that either dribbles out, or is spectacularly (and grossly) sprayed out. Simply put, tubenoses have the superpower of drinking what is normally toxic levels of seawater because they have little kidneys on their fucking faces.

Many of the larger tubenoses, like albatross and petrels, are superbly adapted to long-distance flight, and have a whole suite of traits that maximize their flight efficiency. The most obvious of these is simply their gargantuan wingspan; long, narrow wings allow for soaring much longer without flapping (unlike short, broad wings (like what is found in many familiar songbirds), which are perfect for maneuverability through dense forest or for evading other, predatory birds…but are shitty for traversing an entire ocean’s breadth, since flapping must occur far more frequently to keep aloft). The side-effect of this is that take-off, and landing, are a bit cumbersome. Most short-winged birds have the luxury of just throwing on the brakes and landing wherever they please. However, the big, bulky albatross, for example, has to engage in long swoops to reduce speed enough so that when they do put down their landing gear (ridiculous, floppy, webbed feet that are poorly equipped for walking, and make albatross terrestrial locomotion charmingly awkward) they don’t strike the earth and tumble beak over tail feather. Just this last weekend, I went out to the Natural Area Reserve for nesting Laysan albatross and wedge-tailed shearwaters at Ka’ena Point on the Hawaiian island I live on, O’ahu, and observed first-hand the challenges of the extremely high-aspect ratio wings of large tubenose birds. More than once, one of the Laysan albatross nesting at the site, made a circuitous, looping cut through the windy tropical air, with wingtips coming within not more than thirty feet of the heads of me and my birding companion. I did not see these birds flap even one time in what seemed like the better part of five minutes as they soared in a great ellipse, eventually finding a deacceleration “sweet-spot” and ending their elegant voyage through the heavens and plopping ungracefully on the hot sand below in what is probably one of the most comically stark contrasts of movement in the entire animal kingdom. Watching this occur, one can’t help but be reminded of the spiraling descent that many large commercial jets make before landing. In terms of airborne agility and ease of take-off and landing, if your backyard robin is a Cessna 172 Skyhawk, then your typical giant albatross is an Airbus A380.
In addition to the simple mechanical efficiency afforded by immense, thin wings (wings that are long enough to make the wandering albatross, Diomedea exulans, owner of the largest wingspan of all modern birds, occasionally reaching 12 feet across), the largest tubenoses also have a little trick that makes it even easier to fly without the slightest bit of effort. Some species have a special tendon that actually locks the wing into place once fully extended, so that the wing can stay in that position for hours at a time. You know that little spring catch that keeps an umbrella in the “open” configuration? These birds basically have that technology incorporated into their wing musculature.

So, it can be said that the Procellariiformes, with their Doomsday Prepper-esque self-contained fluid filtration system, built-in Garmin and cruise control, and wings that catch the trades far more effectively than any sail, are part of faction of seafaring birds that make even the hardest, crustiest, beardiest, veteran sea captain look like a quakey-legged, queasy landlubber.

“Aye, everything I am…’tis a lie.”

It is within this already hardy contingent of open-ocean avian gods that the giant petrels (two species of bird within the genus Macronectes) find their relations. These birds, divided into a Northern and Southern species (although both are native to the coastline of Antarctica, and the islands surrounding it) are most closely related to the fulmars, and are, unsurprisingly, a part of the petrel family, Procellariidae. They are the most massive tubenoses with the exception of the regal albatrosses, both of them reaching about the size of an eagle. Outwardly, they don’t appear to be much different than their relatives; muted coloration, large and powerful wings, a hooked beak made up of the nine plates unique to the Procellariiformes, webbed feet, etc. If you were to take a fulmar and beef it up in size a few fold, you’d, at least on the exterior, get a giant petrel.

But the giant petrel has a secret that separates it dramatically from the rest of it’s tubenose kin, a secret buried beneath a deceitful outer visage that makes it appear more as a docile dabbler of the ocean surface (albeit a big and noisy one), rather than the agent of darkness that it actually is. Tubenoses have a diet based upon marine foraging, in which they consume squid, krill and other crustaceans, fish, and occasionally plankton. This is a pretty standard menu among most seabirds and shorebirds. However, somewhere along the line, giant petrels lost their refined taste for sashimi and cocktail shrimp. Giant petrels, instead, primarily fill their bellies with the decayed flesh of beached marine mammals, and fluffy, helpless penguins (sometimes, as this very graphic video illustrates, hollowing out the poor penguin’s body cavity like it was an intestine-filled piñata…while it is still very much alive). Giant petrels are the Antarctic’s answer to vultures, and they take up their ecological role as the cold southern sea’s clean up crew with enthusiasm, beating out all smaller scavengers at whatever felled beast rots on the barren shores of the antipolar continent, diving claw-tipped beak first into the fetid, blubbery jackpot.

Hasn’t given a single fuck in over one million years

And by “enthusiasm” I mean “aggressiveness”…and by “aggressiveness” I mean “pretty sure someone slipped these birds some bath salts.” Giant petrels lay waste to any poor, opportunistic seabird trying to capitalize on the good fortune of a fresh, bloated seal carcass. They are aided by their substantial size advantage over any shorebirds within their home ranges, their strong and sharp bill, and their relatively strong legs (in comparison to their tubenose relatives) that allow them to bear down on their quarry, living or dead, with ease on land. When arriving at a carcass, they adopt a posture designed to make everything with feathers in the vicinity to pack up and get the fuck out; wings arched and outstretched, neck extended with the hooked beak directly facing any contenders, and tail stiffly pointed upwards (an “intimidating” posture I’ve seen similarly employed in testosterone and alcohol-soaked college-age human males). If their “carrion master” pose doesn’t adequately impress, they drop the diplomacy act right quick and get on with beating the everloving shit out of everything around them until they get their way (again…this is something I’ve seen in the wilds of the house-party-full-of-20-year-old-dudes ecosystem).
If undisturbed, they plunge right in, and the formerly intact dead body is torn apart like it was a free pizza thrown to a pit of graduate students (haha, the joke is that we are poor). Apparently evolution didn’t have the foresight to gift these fledgling scavengers the bare neck and face of the vulture, so their feathers on their faces quickly become drenched and sticky with blood and offal. This doesn’t slow them down at all, apparently, because they will run around with this shit plastered all over them like they just waltzed out of the finale of “Carrie”…ravenously waiting to pounce on the next unsuspecting little penguin, or unclaimed corpse on the shoreline.

“You like this color? I think the shade is called ‘screamoglobin’.”

So, obviously, once giant petrels have a meal, they definitely don’t disguise their role as the main purveyors of violence on the Antarctic coast. And violent they are. I’ve already alluded to their impassioned vivisection of penguins, an easy task for them considering that penguins are basically just squishy, clumsily toddling bags of meat. But, they regularly have a go at taking other prey as well, out of necessity. There aren’t a lot of options for blood-thirsty animals like giant petrels in the Antarctic; it’s not like there are a glut of different types of prey animals running around for them to pick from. The great, frigid south is an isolated land without much else than animals that either fly there or swim there, meaning that most everything on the coastline is either a bird or a seal.
Adult seals, especially the gargantuan leopard and southern elephant seals (which can reach weights of 1,300 lbs and 5 tons, respectively), are obviously far too big for a giant petrel to eat (although I wouldn’t put it past these one of these assholes to try). But seal pups? Yeah, those are barely big enough to leave leftovers. It isn’t that uncommon for a group of these soulless bastards to descend upon a seal pup the minute it’s been separated from its parent.
Giant petrels are actually very adept at slaughtering the babies of other animals. They dispatch penguin and albatross chicks with remorseless ease, and just as often as they make the adults their entree of choice. Yes, they even snuff their own close relatives, the albatrosses, and devour them in an act of appalling taxonomic treason.
One thing is certain, if it is cute and defenseless, giant petrels will desire to rend it into tiny, bite-size pieces.

It’s also worth noting that stuff comes out of giant petrel mouths about as often as stuff goes in….because giant petrels are quite fond of vomiting. I should clarify that this isn’t referring to the sweet, altruistic, maternal regurgitation that a great many birds use to feed their chicks. No, giant petrels engage in projectile puking, a la The Exorcist, on a fucking horrifying scale. So, emetophobes beware.
This typically occurs in two distinct types of scenarios. The first is related to the birds’ fondness of food. Being opportunistic foragers, giant petrels tend to eat as much of whatever it is they claim (or slay) as possible, because there’s no guarantee that there will be another meal around the corner…something I can identify with as a graduate student. “Modest portion size” is not a part of their lexicon. They are such, er, “healthy eaters” that early European explorers to the Southern Ocean used to call them “gluttons,” a name probably further supported by the giant petrel’s habit of loitering around sailing vessels, endlessly lusting for food scraps from sailors. Sometimes, these feathered Mr. Creosotes gorge themselves to the point where they are too heavy for take-off. If a human, or anything else that can be considered a predator (something that doesn’t exactly abound in the Antarctic, for much the same reason as why there isn’t much variation in prey…isolation), gives them a spook, they’ll promptly throw their digestive tract on ‘reverse’ and expeditiously shoot a slurry of seal pancreas out all over the ice. Once they are back to their svelte selves, they can muster the strength to take to the air and evade whatever threat forced them to toss their cookies. This is a strategy used by pythons, boas, and me when I accidentally try to jog right after going out for Taco Tuesday.

The other context for this lovely behavior of assertive upchucking comes from a very different place. You see, giant petrels, as well as many other procellariiform birds, have weaponized their barf.
Well, more technically speaking, it’s stomach oil, rather than the partially digested contents of its most recent meal. Stomach oil is a mixture of primarily wax esters (a fatty acid) and triglycerides (major constituent of animal fat and vegetable oil) that is very energy-rich, and is stored not in the stomach itself, but in the proventriculus, which is the first ‘chamber’ of the digestive system of birds, and is sandwiched between the esophagus and gizzard. The oil is a by-product of regular digestion, and most tubenoses make the stuff. It’s thought that it has a role in energy storage for long-distance travel, but it has a far more interesting utility as “get-the-fuck-away-from-me juice.”
Giant petrels are notorious for spraying this crap at would-be attackers, including both predators and combative, rival giant petrels. It isn’t corrosive, like an acid or strong base, but it is still a potently effective chemical weapon. For mammals (including humans), the stomach oil’s revolting stench is its main deterrent. The experience is a bit like getting a cup of rancid salad dressing, two-week old bacon grease, and decomposed escolar splashed right in your face. Since the oil is well…oil…it doesn’t exactly wash out easily with water, so if you are lucky enough to showered with this liquid offering, your clothes will probably be stuck with the nauseating miasma for a very long time. This nasty, skunk-like defense mechanism is also the origin of the giant petrel’s second old-school nickname from maritime explorer times; the “stinker.”
If you are a fellow bird and you get oiled, the consequences can actually be a little more serious. Stomach oil, once cooled by the outside air, solidifies into a waxy product that ends up gluing feathers into matted clumps…and, again, it doesn’t readily dissolve in seawater. Anyone who remembers the tragic effects of the Exxon Valdez oil spill (or the far more recent Deepwater Horizon spill) can recall what happens to seabirds when their feathers are dowsed in sticky, heavy, oily substances.

So, yes, giant petrels aren’t exactly a bunch of charmers. Despite the fact that their goofy, webbed feet make them look like they should be trying to sell you payroll deduction insurance, these birds would certainly make their vicious, extinct, therapod cousins proud.
The Antarctic is inhabited by a creature that is infamous for callously abusing the vulnerable and powerless, habitual greed, a consistently repellent demeanor, and for spouting copious amounts of loathsome filth out of its mouth. And no, I’m not talking about Rush Limbaugh.
The next time you are tempted to schedule a little idyllic excursion to Terra Australis to have a life-changing, grand ol’ time marching with the fucking penguins…remember this princely, dainty beast:


There is another antagonistic avian that frequents the frozen, polar regions of our planet, but unlike the giant petrel, it can be found near both the South and North Poles (but nowhere in-between). It gravitates to the cold, harsh lands and seas, far from the warm embrace of direct sunlight, and perhaps, on a certain symbolic level, appropriately so, given that this creature has a soul as icy and brutal as the places it inhabits.
It is allied closely with the gulls (within the Lari subdivision of the aforementioned shorebird order, Charadriiformes), but it forms its own family (Stercorariidae) within the order. Perhaps even more notably, of the seven species of this group of birds, all of them reside within a single genus (Stercorarius), which is impressive considering that the ranges of some of these apparently closely related species are separated by many thousands of miles. It’s appearance betrays its close relation to the seagulls. It basically looks like a burly, brown gull that’s been excessively hardened by a life scraping out existence on the edge of Earth’s zone of habitability, and with the addition of a beak that looks to be crafted out of scalpel-sharp obsidian, it becomes clear that this bird is doing a bit more than leisurely picking at abandoned fast food in a beach park dumpster.

Stercorarius are common sights both along the coastlines and inland areas of both poles. They are, as I will explain in detail shortly, ecologically important, crafty, and efficient predators in the wilds of high-latitude nations like Russia, Canada, the Alaskan U.S., the British Isles, Scandinavia, Chile, Argentina, and New Zealand (as well as various small island chains and isolated isles in the Arctic and Southern Oceans, sometimes in great numbers). Since they range over such a diversity of nations and human cultures, and are invariably imposing, unforgettable birds, it’s no surprise that they are granted unique names that distinguish them from other shorebirds. In Anglophone areas of the Arctic (Canada, U.K., the U.S.), they are commonly referred to as “jaegers”, which is derived from the German word “Jäger”, which translates to “hunter.” Yes, this is a bird which has a name (notably originating from the tongue of a Teutonic barbarian tribe) that has been associated with 30-story tall robots that beat the piss out of giant, alien sea monsters and a liver-melting liquor that tastes like cough-medicine, bad decisions, and the tears of vanquished foes…so, yes, we are off to an epic start. In Norway, it is known as the “storjo.” In parts of Scotland, the “bonxie.” In the far south of Chile, “págalo.” The Māori of New Zealand (Aotearoa) refer to them as “hakoakoa.” The Japanese know it as “Touzoku-kamome.” However, it is the name it was given by the Faroese (the indigenous Germanic peoples of an island chain between Scotland and Iceland, the Faroe Islands) that has the most usage worldwide; “skúgvur.” This name has subsequently been corrupted to “skua”…not to be confused with “ska”, which is altogether different. For example, the piercing, ear-shredding screech of the skua is far more tolerable than ska.

Skuas also have less brass. Less stupid hats, too. ….I really don’t like ska.

Why does this one group of gull-like birds get their own brand in every language? Sure, they are big, powerful, muscular birds, but they aren’t particularly distinctive in that regard. Most species have dull coloration and plain features. What makes them important enough to be considered appreciably distinct by these high-altitude cultures?
Many times this is because a certain animal has some sort of cultural significance, and it would be reasonable to wonder if the skua holds a special place of reverence in these cultures, reflected by the language. Perhaps they have some sort of role to play in the local mythos. Are they viewed as messengers of changing times, for good or bad? Are there parables about them? Do they represent guardians, or perhaps cosmic villains? Or is their strong, direct flight in the face of biting polar winds something to be admired, and therefore noted? Why has the skua repeatedly carved out a unique spot in the communal psyche of all these cultures, out of a wide diversity of fellow smelly, squawking seabirds?
The answer is that it has less to do with any sort of noble trait that is worth emulating or aspiring to…and more to do with the fact that skuas are, by bird standards, belligerent, unapologetic, hyper-aggressive, inherently amoral assholes. Basically, whenever it came time to name all the birds in each of these areas, it’s almost a guarantee that upon watching the skua for a few hours, whoever had the task of doing so wrote down the following footnote for this nefarious beast: “Note: Easily identifiable by how much of a bag of dicks it is to all the other animals.”

“I heard u were talkin’ shit.”

So, why the bad reputation? Why does this bird get the same amount of esteem as a run-of-the-mill dog fight coordinator? Why does this bird, apparently, deserve its own “Scumbag Skua” internet meme?

Well, most skuas are, at least part of the time, “kleptoparasites.” To get an idea of what kleptoparasitism is consider the following scenario:
You go into work in the morning, and deposit a perfectly crafted sandwich in the break room fridge, storing it there until lunch. You spent a lot of time piecing this masterpiece together, and you are really damn proud of your creation. Gracefully folded slices of glistening, peppered pastrami, an entire garden of exquisitely prepared, fresh veggies, crisp pickles, muted swiss cheese, a healthy splash of stone-ground brown mustard, and you even added a bit of expensive tangy mayo you picked up at the local mom and pop grocer. You wince at even the thought of calling it a “sandwich”; this is glory between two soft, rich, slices of rye.
You’ve wrapped it neatly in paper (never in a goddamn Ziploc bag, that kind of egregiously unsophisticated bullshit would never even occur to you) to let it breathe, and you’ve clearly marked it with your full name in vibrant, cobalt Sharpie ink. Your mouth waters at your desk for a full four hours as you try to work over your rising hunger, your bubbling, painful anticipation. Just when the olfactory siren song that’s been looping in your brain ever since you got that first whiff of your culinary opus currently marinating in the coolness of the company refrigerator becomes unbearable, your lunch hour arrives and you briskly walk back to the break room. You are euphoric. Your hands are quaking, and your stomach is wailing and sending great thunderous bellows throughout your body…but you are elated that your patience has paid off. At long last, you can take part in the gastronomically perfect experience waiting just beyond those dingy refrigerator doors.
You open the fridge, alabaster light blinding you like the brilliant glow of Heaven itself. Your smile falls, the life drains from your eyes and your heart rockets to the bottom of you, and your hunger blackens into bilious despair. Where is it? Dead space on the rack where you placed it. Is this real? You pinch yourself, hoping that you are in a nightmare. No, the welt on your skin confirms your unfortunate reality and you slip into a frantic rage, slamming the door and scouring all surfaces of the room. Maybe someone moved it and forgot to put it back, you delude yourself, eyes tearing, breath rapid and shallow. Your gaze moves to the trash can and you drop to your knees, clasping the thin plastic edges as you will yourself to peer inside.
You cry out. The once carefully, intricately folded paper is in there, carelessly crumpled and empty of its precious contents, wedged in the bottom in a violated ball. The rye crumbs decorating it may as well be blood. You slump back on your heels, catatonic. Defeat. Treachery.
You’ve been sidelined by the demoralizing club of betrayal…one brandished by a very special type of person. That person? That sociopathic wad of ambulatory after-birth that plundered your lunch and lanced your very soul? That was a kleptoparasite.

A kleptoparasite is an animal that gets by, at least part of the time, by stealing prey from other predators…either by force, or by conniving thievery…as in the sandwich example. The term literally means “parasite by way of stealing”, where the Greek prefix ‘kleptes’ means ‘thief.’ A kleptoparasite is one who engages in unrepentant food looting, at any cost, and skuas are archetypal examples of those that uphold this, er, lifestyle choice.

Skuas are tenacious and fearless thieves, and don’t appear to have any qualms about barreling face first into an animal holding a fresh kill, all sharp beak and wings and shrill screaming. More often than not, this is enough to get the poor animal (almost invariably another predatory bird) to drop its prize, which can be a small mammal, another bird, or most often, a fish. Size of the target is also not much of an issue, which is astounding, considering that while skuas are big as far as shorebirds go, they often take on animals that are several times their mass; in the Arctic this can be a large eagle or a heron, and in the Antarctic this can be the oh-so lovely, blood-soaked, vomiting dynamo that is the giant petrel I described above. One well-placed hammering of an eagle’s scythe-shaped beak, or one oil bath from an ornery giant petrel, could ruin a skua’s week and/or potentially kill it. But the skua has…moxie…and goes right the fuck in there anyways…and on a regular basis, wins. This is sort of the equivalent of someone attempting to rob a bank, which happens to be filled with a dozen armed police officers, by barging in completely in the nude, screaming into a megaphone, and proceeding to wildly slap everyone in the vicinity…and somehow coming out not only alive, but with armfuls of Benjamins.
Skuas really don’t seem to care, and even if the situation is too hopelessly dangerous to take on headfirst by themselves, they’ll sit back and wait for an opportunity…or simply gather more of their criminal friends so they can organize an “Italian Job” style raid later. Threat of crippling injury and excruciating death be damned.
Skuas truly are the honey badgers of the bird world.

While many times the target is a something as simple as a seagull or a tern innocently trying to hork down a few herring, they will sometimes congregate around a seal or whale carcass…which inevitably results in tense showdowns over the spoils between other species of unscrupulous scavenging animals. I find it splendidly dinosaurian.

I fail to see any difference between these two images.

When skuas aren’t harassing and bullying everything around the polar schoolyard trying to score an easy meal, they are shrewd, opportunistic predators…more than capable of killing for themselves if they need to. Much of the time, their diet consists of small to medium-sized fish, and a smaller complex of species in the Arctic (the ones most commonly referred to as jaegers) are partial to feeding upon small mammals like lemmings. However, they will routinely attack adult penguins, which are many, many times their size…but not to kill and eat them. You see, adult penguins, during certain parts of the year, hide tasty, vulnerable morsels that a skua can more than handle. I’m talking about penguin eggs and tiny, fuzzy penguin chicks, both which are protected by the skin flaps around the feet of the comparatively gigantic parent. All the skua needs to do is distract the adult with repeated stabbing with its spur-shaped beak, and it can root in underneath and dislodge the helpless egg or baby with lightning fast precision.
It’s like the story of David and Goliath…if David nonchalantly gulped down Goliath’s infant children as effortlessly as Kobayashi inhales hotdogs.
Nothing is safe. When a skua is around, there’s a good chance someone is going to die. Cute puffins? Pathetically one-sided aerial dogfight ends predictably violently. Dead. Oystercatcher, minding its own business? Head dashed against rocks. Also dead. One of those coveted penguin eggs? Over-easy. Full grown sheep? Fuck them too.
The skua, cold, calculating, exceptionally bright, and not squeamish about brutally taking what it desires, would have been a fine pet choice for Gordon Gekko. This bird, this depraved, deadly amalgamation of seagull, hyena, and butterfly knife, has a moral compass so twisted and rusty it’d make any serial killer blush.

“That’s a nice baby penguin you got there. It’d be a shame if something were to…happen…to it.”

But, the skua does manage to consciously spare one being from its sadistic bloodshed…its own progeny. Yes, the only thing that isn’t subjected to intimidation and violence from these delinquents are young skuas and skua eggs. Their vicious habits don’t extend into cannibalism (although the young chicks typically have a Spartan upbringing, which ends up resulting in fratricide in the nest…so yeah, they start off with the murdering in the cradle), which I suppose is to be expected.
For their eggs and young, skuas channel the unbridled machinery of their malevolence towards an aggressive defense of the nest, where they unflinchingly dive-bomb anything that strays too close (including humans). So, you know, there are no baby showers at the Stercorarius residence.
This strategy of recklessly swooping at everything that moves, with all the paranoia of a meth-head renting a space below a guy who watches Cops really loudly, is sometimes combined with a behavior unique to some populations of skua that may potentially be a boon to fitness. In some populations of the brown skua, Stercorarius lonnbergi, off the coast of New Zealand in an island chain known as the Chatham Islands, the mating system of choice is of the cooperative variety. That is, specifically speaking, polyandry; in which one lady bird is paired with two or more gentleman birds. This setup occurs in other bird species from time to time, but almost always in really stable, terrestrial, non-migratory species that experience very high population density. Shorebirds and seabirds are almost unfailingly monogamous, so this breeding behavior in these specific populations of skuas is a bit unprecedented. We don’t yet understand if this reverse harem situation is conferring some sort of special evolutionary benefit to skuas residing in this specific island chain, or why this breeding system developed in the first place.
One thing is certain; despite the skua’s off-putting veneer of blood-lust, carnage, and unfeeling, surgical dismemberment of baby animals…deep down, they have a soft spot for their kids. I find it appropriate that a bird that makes a living exploiting, extorting, manipulating, and terrorizing everything around them would, through their strong parental defense and support of offspring, accurately emulate the multi-generational organization of a crime family.

The third entry in this list is one that lives about as far away from a marine environment as possible; up in the highest plateaus and mountains of Eurasia and Africa. It is a “proper” bird of prey (meaning that it belongs the order containing familiar raptors like hawks and eagles, Accipitriformes), and maybe it might seem like a cop out to include something that has more conventionally T-Rex-like behavior (i.e. flaying lesser beasts with its claws and face) considering this list is supposed to honor the weird, obscure, and surprising…but I think you’ll be able to see why I’ve made an exception in this case.

Why’s that? Well, this bird, known to many as the bearded vulture, or lammergeier (Gypaetus barbatus, to the ornithologist crowd), looks like a goddamned for-real dragon.

Pretty sure this resplendent fucker flew straight out of a Dethklok music video.

Smaug up there is actually just a vulture in name only, and is actually not that closely related to the naked-headed incarnations of vulturedom most of us are familiar with. It’s closest relative is another “vulture” from various parts of the old world (Neophron percnopterus, sometimes known as the “Pharaoh’s chicken” or, more commonly, the Eqyptian vulture), and together, these two species, alone in their respective genera, are thought to form a unique subfamily (Gypaetinae) within the greater hawk/eagle/vulture/buzzard family (Accipitridae). Lammergeiers are exceptionally uncommon, but, as a species, they don’t seem to be threatened with extinction (although there are some localized threats). Instead, their scarcity is likely a natural consequence of their truly expansive home ranges throughout mountainous territory that generally doesn’t have the food resources available to support large, dense populations of bearded vultures anyways.

…not that there should ever be any reason to doubt the lammergeier’s resilience in the face of humanity because LOOK AT IT. Seriously, this thing doesn’t even look mortal, let alone even remotely concerned with the meddling of us ground-tethered peasants. The lammergeier does seem almost entirely separated from the goings on of the rest of the animal kingdom, since it casually hangs out further up in the mountains than even the trees can grow. These heights can be 16,000 feet or more above sea level; far enough up that most humans can’t even get enough oxygen into their bodies to maintain normal physiological status…which generally includes not hallucinating, puking everywhere, and bleeding from your eyes and nose. Not only does it thrive in places that are inaccessible to humans primarily because they are that much closer to the vacuum of outer goddamn space, but it’s been known to hang out near the summit of Mt. Everest. Yes, this bird makes the highest peak on the planet, the global “Mt. Olympus”, its playground.

In addition to the apparently borderline divine character enveloping the lammergeier, is its general aesthetic embodiment of the hyper-masculine, coke-fueled fantasy themes surrounding performances and album art of metal bands of the early 1980s…an element I very much appreciate about this animal. The lammergeier looks like a literal god of rock and roll, birthed from the strings of the very first electric guitar…a being, once summoned, that arrives by ripping through the heavens, propelled purely by 170 decibels of space-time splitting vocal belt, a trail of blow and pyrotechnics in its wake, with eyes bloodshot from the strain of being so awesome. I mean for Christ’s sake, even its name, “lammergeier”, sounds like a damn Rammstein album name. This is less of a bird, and more of fire-eyed wyvern, aloft on great wings, slicing through craggy canyons and scaling glaciated mountain passes, while lightning strikes and alights the roofs of mountain cottages aflame in time with a vociferous bass line.

Somewhere, the ghost of Ronnie James Dio is creaming his jeans.

Oh, and it has a beard…because of course it does.

Surely, you say, such a powerful and otherworldly thing must be a force that instills widespread fear among all animals in the uplands of the Old World. How many metric tons of yak does it consume weekly? Have the Nords of Skyrim learned how to quell its anger by use of archaic, magic incantations? Does it burninate the countryside annually, or just during election years? Do goats sacrifice themselves when a dark shadow passes overhead?
These questions, which I am 100% sure you are asking yourself, are fair…but despite its appearance, there is a good reason it is known as a “vulture”, and that reason is its primarily scavenging lifestyle. A bit of confusion comes in when you examine the German translation behind the other common name, “lammergeier”; it means “lamb-hawk”, and is based upon the old, erroneous, belief that these birds are sheep slayers. It does occasionally take live prey, but it gets most of its nutrition from the deceased.
Before you fold your arms over your chest and pout about your rapidly diminishing opinion of real-life Roc that you preemptively thought palmed horses like a basketball and caused avalanches with its devilish screams, and chalk up this bird to being nothing more than a hermit eagle that has a hairstyle that makes it resemble a cooler version of a Thatcher-era Rod Stewart…know that the manner in which the lammergeier scavenges is like no other vertebrate on Earth.

When a large animal perishes in the wild, vultures are the stereotypical “early birds” to the site of the rotting carcass. They track down the meal by way of both keen eyesight and smell, and in no time are ripping into the bloated bag of goodies. With the aid of scavenging mammals, insects, and additional bacteria decomposition, the dead animal is stripped of flesh/organs/everything in no time, leaving a dry, sun-bleached skeleton. To most animals, and certainly to most birds, at this point in the scavenging/decomposition timeline, the skeleton is a fairly useless food item. It’s caloric capacity has been completely extinguished.
But none of these rules apply to the lammergeier, because the lammergeier eats bones. Not bone marrow; that succulent treasure inside large bones is a treat held in high regard by a wide variety of animals. No, the lammergeier eats bones. Sure, there’s marrow attached to it, but the bones are swallowed right along with it. Straight up.

Consumption of bones as a major form of sustenance isn’t exactly common in nature. Meat and skin and offal are all far easier to digest, easier to get to, and very nutritive…bones are far less so for all of these things. Specialization in eating something as…rugged…as bones is, unsurprisingly, an uncommon evolutionary and dietary strategy when there’s so much muscle to glean from. Why eat the “stick” of the drumstick?
There are few organisms that prefer the hard stuff, and one notable example are the bone-boring worms (Osedax) that mow down on whale skeletons once they sink to the dark floor of the ocean. There is a single type of fly, the bone-skipper, which up until last year was considered extinct for the better part of a century and a half, that eerily mimics the lammergeier’s preference for bodies in late decay…although it doesn’t necessary eat the bone matrix itself, and instead breeds and lays eggs within the marrow of pre-broken bones. But these examples are both invertebrates, and osteophagy (bone eating) doesn’t really occur in vertebrates outside of the occasional herbivorous mammal supplementing its diet with the minerals from bones. The lammergeier’s making its livelihood primarily off of bone consumption is a unique one among birds, most assuredly.

So, how does it accomplish this? The first step is to make sure the bone is in manageable pieces. The lammergeier is strong enough to break and crush smaller pieces of bone it acquires with its beak, but for larger bones like the femus and the pelvis, more drastic measures must be taken.
These “drastic measures” include gripping a substantially sized bone in the talons, potentially weighing as much as the bird itself, and flying off with it. The bird makes a direct flight to a spot directly several hundred feet above a collection of particularly hard and jagged rocks, where it lets go of the bone, leaving gravity to do the work of splintering the bone into shards that can be easily swallowed. I like to call this the “Newton method,” and it’s something that other birds (like crows) have done with hard nuts and snail shells on hard rocks or asphalt surfaces.
The lammergeier then swoops down, checks out to see if it was successful, and if so, gobbles up the best pieces and surveys its territory for additional bones.
It’s because of this behavior that one of its oldest names is the “ossifrage”, which means “breaker of bones.” In Arab cultures, it was once called “al-kasir”, which roughly translates to “shatterer” or “breaker.”
I have a hard time conceiving of a more badass series of names for an animal that looks as Herculean as the lammergeier.

Notably, this species uses the exact same method to dispatch living tortoises. The same system is used to smash the turtles’ shells, allowing easy access to everything inside. Supposedly, the ancient Greek playright, Aeschylus, was killed when he was struck in the head by a fucking tortoise falling out of the sky in the year 456 B.C. According to the story, the tortoise was dropped by an “eagle” that apparently thought the shiny top of Aeschylus’s head was the perfect place to cleave the reptile in two. Given the known habit of tortoise tossing by lammergeier’s, it’s possible that this species was actually the “eagle.”
Or, alternatively, someone just made up all that shit.

If you sat down and tried to eat several handfuls of bone shards and marrow, assuming you wouldn’t choke on their descent through your puny, non-lammergeier-esophagus-of-steel, you would end up having a bad time. That would be a one-way ticket to a night in the Painsville emergency room. Human stomachs, and the stomachs of a great many other vertebrates, aren’t up to the task of digesting bone even remotely close to completely.
However, the lammergeier has a second trick. Not up its sleeve, but deep in its stomach. The lammergeier has remarkably strong stomach acid. I’m talking xenomorph blood strong, and this highly-concentrated, acidic environment in the stomach much more quickly dissolves both bone and the marrow inside than anything you are I could muster from our own inadequate digestive chemistries.
For some context, human stomach acid is a hydrochloric acid solution that hovers around pH 1.5. This is about the acidity of lemon juice, maybe a bit stronger. Lammergeier stomach acid has a pH of half that, meaning that the concentration of acid in the bird’s stomach is an order of magnitude higher, and approximates the corrosive nature of battery acid.
Basically, if a lammergeier were to projectile vomit all over you giant petrel-style, the stomach acid would take the finish off your face like you were a Nazi taking a peek at the Ark of the Covenant.

If you still aren’t convinced that the lammergeier is the most ludicrously hardcore bird to honor our planet in the modern era, get a load of how these animals go about making baby bone-destroyers.
Lammergeiers relinquish their hold on their stately, solitary lifestyle cruising between cliffs, scanning their world for woefully unsmashed bones, for one thing only; to…well, bone, so to speak. And it is a sight to behold. Apparently, when two such supernaturally awesome creatures come into close contact with one another, the fabric of the universe that binds basic physics together breaks down. The meeting of complementary lammergeiers for the purpose of copulation is like breaking the speed of light….the consequences are breathtaking and a little terrifying.
The courtship display begins (presumably after deafening, introductory mating calls made up of nothing but brain liquefying guitar solos and thunderclaps) with the lammergeiers meeting in mid-air. This followed by a spiraling, acrobatic dance a thousand feet above the rocks below, full of free-fall plummets back down to earth, talons locked together, only to separate at the last possible moment and start over again. The performance, full of unfathomable g-forces, in-flight engaging and disengaging, resembles a season-ending, frenetic fight scene in Dragonball Z, not foreplay. Hills crumble. Storm clouds gather. Zeus himself watches from on high and weeps, in awe…and to be honest, a little bit of arousal.
Eventually, the deed is done, and another one or two kings or queens of the Ceiling of the World are hatched the coming months.

So, the lammergeier may not be a flame-spitting feathered serpent summoned directly out of a Tenacious D song, but it certainly looks the part. Lammergeier are, in actuality, not particularly aggressive (they don’t even really make noises, let alone battle with other organisms)…but only because they never need to be.
They are the solemn, patient tail-end of the scavenging train in their ecosystem. They have no interest in the chaos of devouring viscera that their bare-headed cousins engage in. They are content to wait until the skeleton’s riches go unappreciated. Lammergeiers aren’t ‘angry birds’ in that sense, in the way of the skua and the giant petrel. But they hold a symbolic role in their world that I find significantly more chilling:
Other scavengers, the crows, griffon vultures, jackals, maggots, beetles, hyenas, etc., remove everything but the framework of the animal, the scaffolding, the internal structure that the skeleton provides. Without the lammergeier, these would slowly be corroded by high-altitude wind and sun, bleaching and powderizing over hundreds of years, perhaps even fossilizing. The lammergeier steps in and acts as a force of nature, blazing through eons of environmental erosion within the caustic chamber of its own gullet. It is in this sense that the lammergeier fully breaks down the remains of the animal, even the last, hard leftovers, and actually forms, directly, the last link in the circle of life. The last link that returns the deceased animal’s carbon, nitrogen, and amino acids right back into the earth.
It is in this way, this inescapable finality that this bird provides, that the lammergeier is the most appropriate avatar to associate with Death. Other scavengers clean up the mess. The lammergeier brings them Home.

Image credits:shoebill intro image,potoo,sea captain,giant petrel in snow, giant petrel eating seal, bloody giant petrel (Laurent Demongin), bloody giant petrel (face) (Laurent Demongin), skua in flight, skua face, skua and penguins, skuas and giant petrel, dinosaur showdown paleoart credit to: “Thunder Across the Delta”, Mark Hallett (1996), lammergeier, lammergeier in flight

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.


Arachnids: Pseudoscorpions


It probably does little to assuage the unsavory first impressions one has with the subject of the third group featured in this blog’s arachnid series, the pseudoscorpion, by noting that its name literally means “false scorpion.” Perhaps this is no surprise, given that without the proper context, pseudoscorpions are intimidating both in their name and in their generally “icky” appearance, armed with menacing claws, attached to a body that resembles a lightbulb made out of alligator skin. If nothing else, you’d at least be somewhat justified in being suspicious of them. Looks like a scorpion, has “scorpion” right in the name, but isn’t a real scorpion? Please. Just what is that tailless son of a bitch hiding? Maybe you doubt that there is such an animal, and the photo above simply depicts a normal scorpion, sans its stinging tail, removed by Photoshop. “What kind of rube do you take me for, blogger on the Internet?! I do not take kindly to unprovoked trickery!”, you howl, with language curiously more sophisticated than what is normal for someone so enraged.

The thing is, pseudoscorpions really are a unique group of arachnids distinct from “true scorpions.” They are partitioned off from the rest of the arachnids in their own taxonomic order, the predictably-named Pseudoscorpionida (also called Chelonethida). It is thought that in the Great Arachnid Family Tree, pseudoscorpions represent one of several springy arms forking off from a massive branch known as Dromopoda, which also includes potential sister groups like harvestmen (think daddy longlegs), “actual” scorpions (the nasty, pinchy, venomous kind), and solifugids (the infamous “camel spiders” of Internet renown, the subject of urban legends stemming from U.S. soldiers’ alleged interactions with them during the Iraq War…and a tasty snack for Bear Grylls). There is some disagreement within the scientific community about the Dromopoda division, and whether or not it is a true, monophyletic group (monophyletic meaning that it’s a defined grouping on a tree including a species and all of its descendants; for example, the grouping of “reptiles” excludes mammals and birds, and would exhibit something known as paraphyly…however “amniotes” includes ALL the descendants of the amniote common ancestor (birds, lizards, mammals, snakes, turtles, etc.) and would constitute a legitimate, monophyletic taxon), but even if Dromopoda isn’t a cohesive evolutionary unit, it is still likely that pseudoscorpions, based on a combination of morphological and molecular characters, are closely allied, evolutionarily, with many of those “Dromopodan” orders.
So yes, pseudoscorpions are kissing cousins with desert-terrorizing nightmares like scorpions and camel spiders, and those gangly, spider-lookin’ things that collect as corpses in the lonely corners of your garage every summer.

Unlike with the other previously featured, underappreciated arachnid orders, hooded tickspiders and tailless whip scorpions, the reason pseudoscorpions aren’t that familiar to most folks doesn’t have origins in low species diversity, overall rarity, or being restricted to remote habitats in the wilds of the tropical zone. Pseudoscorpionida sports more than 3,000 species in over 400 genera…which is a shit load. Furthermore, additional species are being recorded all the goddamned time; one species was recently discovered right smack in the middle of arguably the busiest and boot-trampled National Park in the U.S., Yosemite National Park. Another was found lurking in a cave system in the Colorado Rockies, like some kind of tiny, lobster-clawed Gollum.
Their range is ridiculously expansive, with pseudoscorpions being described from frigid mountaintops and the Canadian north, to the equatorial jungles, to small, isolated island chains, to even, apparently, under the fucking ground. They seem to show up pretty much everywhere outside of Antarctica, which is a biogeographic trait held in common with not much else outside of bacteria…and humans.
So, what is it? If there are so many of them, and they are supposedly EVERYWHERE, why don’t we see them all the time? Why do we not have pseudoscorpions pouring into the seams of doorjams when the bite of winter descends, like we do with spiders and other domestic arthropods? Why don’t we spy them in the city park alongside butterflies and ants?

Quite frankly, a huge part of the answer is that pseudoscorpions are uniformly Lilliputian. This is in contrast with true scorpions, which have representatives that can weigh as much as a hamster. The largest species of pseudoscorpion flirt with a centimeter in length, but most species are about as long as a dime is thick. These guys could theoretically, comfortably use one of the wrinkles on your thumb knuckle as a cozy blanket. That’s right, pseudoscorpions, the Joe Pescis of the arachnid world, are wee little fuckers, hardly discernible with the naked eye. Because of this, only incredibly close observation outdoors, or a chance encounter with one crawling across an unnaturally light surface (like a painted, indoor wall), will yield an interaction with these strange arachnids.

Pseudoscorpions fairly conservatively follow the standard arachnid bauplan (four pairs of legs, two main body segments, pedipalps, chelicerae, etc.) and while most folks would describe them as “basically a scorpion without the tail”, I think they look like someone took a termite and a crab and smashed them together, end to end.

Just don’t expect this guy to sing “Under the Sea”

It’s probably those crab-like pincers that are the stand-out characteristic of the pseudoscorpion. They are modified pedipalps, the same leg-like appendages that gave rise to true scorpion pincers, the spiked, raptorial arms of the amblypygids, and the simple “feelers” of spiders. These pincers, and accompanying pedipalp “arms”, are often incredibly large in proportion to the rest of the body. While their primary purpose is to pin down and immobilize prey, which consists of arthopods even smaller than themselves, these pint-sized pliers are also instrumental in getting the pseudoscorpion from place to place. Pseudoscorpions are arachnids, and do not have sensory antennae to help them navigate their environment like insects and other arthropods do; an element of life that is not assisted by the fact that pseudoscorpions, regular inhabitants of Earth’s less-than-illuminated places, have very poor eyesight, and many species are flat out blind. However, the pedipalp pincers help fill that sensory role. Most species’ pedipalps (in addition to various other areas on their bodies) are covered in long bristles (called “trichobothria”) that are highly sensitive to minute disturbances and vibrations in the air, acting like a battery of some sort of fine-tuned aerial seismographs, and help give the pseudoscorpion an idea of what the hell is in front of it, behind it, and all around it with amazing acuity. So, when a pseudoscorpion moves along, pedipalps extended far in front, these appendages act like a combination of a white cane and a Nifty Nabber.

The other, more obvious role, of the pedipalp pincers deviates away from the “touchy-feely” and into the realm of the “slicey-crunchy”. Make no mistake, pseudoscorpions are brutal predators, and will mercilessly slaughter whatever tender, defenseless critter that they decide is food (see: just about everything small enough). To us, a pseudoscorpion can be flung off a desk with not much more than a heavy sigh, but in the world of the very tiny, pseudoscorpions possess all the formidability of a Bengal tiger. If a wayward mite, ant, or larvae finds itself hopelessly stuck in the path of a hungry pseudoscorpion, their options are limited to a) defecating in abject terror and/or b) hastily praying to whatever god arthropods pray to that they are spared a slow death.
Such pleading for divine compassion would be fruitless, however. Death at the scissor-like hands of a pseudoscorpion is an agonizing experience for the captured prey animal. The first step the pseudoscorpion takes in slaying its meal has its roots in the anatomy of its pincers. Like a lobster’s claw, the pincer is divided into a stationary half and a mobile half, the latter of which does the actual clamping action. The mobile claw contains a venom gland and duct that runs to the pointed tip. When prey is captured in the pedipalp, the venom is promptly injected into the poor soul’s innards. This venom isn’t designed to necessarily kill the animal, just to get it to stop its pathetic struggling. Once the prey ceases trying, in vain, to escape, it is pulled towards the mouth and gnashing chelicerae, where a saliva-like fluid full of corrosive enzymes is slobbered all over its immobilized, but still very alive, body. To get an idea of what that’d be like in our big, macroscopic world, imagine a cougar attacking a deer (or human) by shooting it with a fast-acting tranquilizer dart, and then casually vomiting industrial-strength lye all over it. Lovely.

“Come on, who wants a hug?”

This World’s Grisliest Act of Digestion takes place all over the globe, in many different varieties of habitats. Like I’ve previously noted, pseudoscorpions are master colonizers, having some kind of presence on just about every major and minor landmass other than Antarctica. The sun never sets on their empire, even if to us, it’s practically invisible. They are found in all the stereotypical arachnid places; wedged under tree bark or rocks, ambling around in leaf litter or soil, crouching in subterranean hollows, and even in the intertidal zone, nimbly moving around barnacles and mussels in their search for food at low tide.
They are most commonly encountered by humans indoors, and usually within the pages of an old, dusty book. On it’s face, such a fact seems a bit ludicrous. In books? Why? Pseudoscorpions can’t even fucking read.

“Oh, hey man. Don’t mind me. Just finishing up some Hemingway.

It’s thought that the “cover to cover” ecosystem is particularly attractive to pseudoscorpions due to the abundance of booklice (primitive insects of the order Psocoptera) living within the ancient, neglected tomes. Booklice, wingless, tiny, and slow, are sitting ducks in the wake of a hungry, claw-bound pseudoscorpion. Chances are, the pages of that old copy of Across Five Aprils in your bookshelf that your grandfather gave you are the site of both literary and literal bloodbaths, the inner spine festooned with enumerable, nearly microscopic, petrified carcasses of booklice, evidence of many past meals left behind by pseudoscorpions. Because booklice cause significant damage to old books, the presence of predators like pseudoscorpions routinely crawling in and culling the herd is pretty beneficial to any bibliophilic human.
Pseudoscorpions also dine on other troublesome indoor pests, like mites, and the larvae of carpet beetles and clothes moths. By doing this, pseudoscorpions assist us in working to eradicate economically disruptive animals that are out of our reach, by being too elusive or simply too small. Screw calling the Orkin man, just let a few thousand pseudoscorpions loose in your home and call ‘er good.

How is that these itty bitty critters manage to get everywhere on the planet, nevermind into every nook and cranny of your house? They can’t fly or swim across oceans, and are limited to not much more than clumsily and blindly scanning the dirt for prey.
The secret lies in a habit of theirs called “phoresy.” Phoresy is when an animal attaches itself to another, larger animal purely for transportation. This happens a lot with other arthropods. Mites, for example, will bum a ride from place to place on much larger insects like flies or beetles. In the case of pseudoscorpions, flies and beetles are also typically used, as well as mammals. The process is pretty straight forward. A large flying insect lands nearby, and before it can take off again, the pseudoscorpion slyly edges close, clasps onto a leg, antennae, or undercarriage of the body with its mighty claws, and prepares for takeoff. The little guys manage to hang on for dear life while being propelled through the air at what is, for them, speeds comparable to a cruising commercial airliner. The intrepid voyagers eventually, either by choice, or by accidental loss of grip, skydive from their six-legged taxi into what is hopefully greener pastures, with bountiful resources.
Pseudoscorpions essentially turn any comparatively big, highly-mobile animal into an unwitting chauffeur, allowing them to glean rides across vast bodies of water and mountain ranges (or accidentally into our homes). It’s possible this ability of pseudoscorpions to stick up a claw along a fly-packed strip of tree branch, and hitchhike to places traditionally far out of their reach, is at least partially responsible for their extremely widespread distribution.

“Alright, I’m on. Let’s Christopher McCandless the fuck outta here.”

Some species can take this non-consensual carpooling to extreme levels. One example is tropical pseudoscorpions native to Central and South America that associate with rotting components of fig trees. These pseudoscorpions (as colorfully outlined in Dr. Olivia Judson’s book Dr. Tatiana’s Sex Advice to All Creation) escape the dearth of food and mate resources in their decaying, wooden home by hitching a ride on newly adult harlequin beetles (Acrocinus longimanus), emerging from the wood below. The phoretic fate of pseudoscorpions traveling this way is, on one hand, fairly traditional, with a main objective being the ultimate arrival at fresh logs with lots of food and shelter. However, since as many as two dozen pseudoscorpions, of both sexes, can stow away on the back of a gargantuan, bulky, harlequin beetle, the brief road trip can serve a second function; procreation.
The crowded, sweaty cargo hold of an airborne harlequin beetle quickly transitions from uncomfortable, stuffy ordeal in coach, to a sexy, co-ed, party bus type of situation. The pseudoscorpions waste little time on introductions and get straight to the boning, undoubtedly much to the chagrin of their poor beetle host, which has no other choice but to wait out twenty-some inconsiderate assholes engaging in an orgy in the inaccessible, impossible-to-scrub pocket under the wings.
To get an idea of the perspective of the harlequin beetle in all of this, imagine rolling out of bed, getting into your SUV to go off to work, and as soon as you start the engine and put it into drive, a throng of horny teenagers stream out of the bushes by your driveway, and aggressively force themselves into your vehicle, where they promptly begin to disrobe and fuck like there’s no tomorrow. Any pleas for them to stop are completely ineffectual, so you do your best to concentrate on the road and drive on. Oh, and you just so happen to have the pleasure of an hour long commute to work.
Pity the harlequin beetle, completely without dignity; the first few moments of its adult life spent smothered by the sex lives of other creatures.

While in this particular case, pseudoscorpion sex can seem free-spirited, haphazard, and anonymous, without much courtship or consideration behind mating choices, this isn’t the case for most members of the order. Pseudoscorpion reproduction tends to be somewhat complicated, with many species employing elaborate mating rituals. Some species mate in a manner similar to hooded tickspiders (examined in the previous entry in this arachnid series), in which a spermatophore, after careful and delicate positioning by the male, is forcibly splattered in the female’s gonopore.
In some species of pseudoscorpion, the male produces a stalked spermatophore that fastens to the ground. Then, through a complex “mating dance”, the male leads (and by “leads”, I mean “drags”) a targeted female closer and closer to where the spermatophore has been deposited. Eventually, after much insincere gallantry on the part of the male, she is positioned over the spermatophore, it is deposited inside of her, and bingo, the deed is done.

“Come on, goddamnit. Closer…closer….clooooser…”

Pseudoscorpions are the benign neighbors you’ve never heard about, dutifully hunting down indoor pests behind the scenes throughout the warmer months (and just calmly waiting out the winter by sealing themselves up in stasis inside a silken cocoon). They are to be respected for this reason, being of a unique class of arthropod predators that get rid of the things that irritate us, and yet have no capacity for harming us. Even a few representatives of their relatives, the spiders, also viewed as economically and ecologically beneficial, are very able, and willing, to hurt us. With pseudoscorpions, it’s a win-win for us.
That being said, these odd dwarves of the arachnid world, are inarguably sociopathic moochers. They remorselessly latch onto other hapless animals for free transportation (and NEVER pay for gas), they copulate wherever they please without any consideration of restraint, and the males have, at best, coercive sexual behaviors. Actually, that description sounds disturbingly similar to acquaintances from my college years…
Anyways, pseudoscorpions are harmless to humans, and provide a net benefit in our day to day lives. But from the point of view of just about anything with antennae and an exoskeleton, these manipulative, Napoleonic pricks are a scourge, “blessed” with talents in all realms of douchebaggery and general dickishness. Whether it’s a venomous pincer suddenly lancing your body cavity, or the drone of an obnoxiously condescending lecture inspired by a year spent vacationing in the pages of Kant’s “Critique of Pure Reason”, pseudoscorpions are a pain in the ass of a great many of the littler members of the animal kingdom.

Image credits: Introductory image, 2nd pseudoscorpion, 3rd pseudoscorpion, pseudoscorpion in book, phoretic pseudoscorpion on fly, dancers

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Electric fishes


It’s hard to imagine modern life without the stuff. It heats, cools, and lights up our homes and businesses, reduces the chaos of transportation, and because it powers technologies that allow for communication across vast geographic areas, it is the lifeblood of the Information Age. Over time, we’ve discovered that the utility of electricity is ludicrously diverse; from keeping food cold enough to prolong preservation, to saving lives through defibrillation of the heart, to being a dick to your friends. The fact that I am currently writing this on a laptop computer, and then disseminating the information in it over the medium of the Internet, is an undeniable consequence of humankind’s harnessing of electrical energy.

If you are inclined to think of the control and use of electrical energy as a human “invention”, then prepare to set your anthropocentrism…and perhaps yarns telling of curious, bespectacled statesmen armed with kites and keys…aside. Humans are far behind the curve, by many millions of years, on this front once the rest of the animal kingdom is considered, because just like with light (which I’ve talked about before), many animals can produce their own electricity.The overwhelming majority of these animals are at least partially aquatic, since water is a far better conductor of electricity than air. Of these gifted organisms, the bulk of them are vertebrates, and in particular, among our finned and gilled friends, the fishes. There are some mammalian exceptions, including monotremes (the platypus and echidna) and perhaps a species of dolphin or two, but by and large, it’s fish that have locked down this electricity thing. Volta, Tesla, and Edison were great and all, but the reality is that animals not too distantly related to the flaky goodness in your Gorton’s fishsticks had them solidly beat by eons, evolving a commanding grasp of the power of electricity right into their bodies.

On a microscopic scale, there are electrical properties observable in essentially all animal, plant, and fungal cells, as there is an inherent voltage difference maintained between the surface of the cell membrane and the interior of the cell. This voltage condition stays stagnant in most cells, but in some animal cells, like nerve and muscle cells, the electrical membrane potential can quickly rise and fall (generating the release of an “action potential”; see: neurons in brain “firing”) through use of special gates in the membrane that pump charged atoms (ex., sodium ions) across the membrane in an incredibly fast cycle of increasing electrical potential, followed by sudden, temporary, dramatic reversal of membrane polarity. This process is critical to the response of these cells to external stimuli, the facilitation of intercellular communication, and, ultimately, the relay of information through cellular circuits. Your neural, muscular, and hormonal systems are made useful by the tightly orchestrated rhythm of many trillions of daily electrical impulses from innumerable, tiny, cellular batteries. Every thought, every heartbeat, every movement you’ve experienced has been instigated by the flashing of all-or-nothing action potential spikes. Your life, from the perspective of your excitable systems, is a bit like an 80 year long rave, faithfully illuminated by the regular pulsing of strobe lights…but with less MDMA and ketamine.

Cellular level mastery of electricity is nearly universal in the animal kingdom, however, and the capacity of the “electric fishes” to step it up to the scale of the whole organism is something special. This generally occurs in two forms: electroreception, which is more common and involves the ability to perceive natural electrical fields as a kind of “sixth sense”, and bioelectrogenesis, which is when the animal actually produces an electric field or discharge. Many electrogenic fish, which are the focus of this entry (because they are badass), are also electroreceptive, and can use their produced electrical ‘aura’ to enhance their perception of their environment, or even communicate with other members of the same species.

“Baby girl, turn me on with your electric feel…”

Perhaps the most obvious example of bioelectrogenesis in fish is the electric eel (Electrophorus electricus…no surprises there). It’s not technically a “true eel” (fishes in the order Anguilliformes), and is actually a knifefish (order Gymnotiformes), a group of slender,  freshwater fish found exclusively in South America that are related to catfish, carp, and minnows. All knifefish have the ability to produce an electrical field, but this power is excessively enhanced in good ol’ Electrophorus, which also happens to be the largest member of the Gymnotiformes, reaching the length of a couch.

Much of that impressive length is made up of the electric organs. These organs, common to all electric fish, are made up of evolutionarily-derived muscle or nerve cells, called electrocytes. Electrocytes are disc-shaped and stacked closely together (think Pringles chips layered in their container), so that each one adds to the total difference in electrical potential, somewhat like a voltaic pile, or the plates in the lead-acid battery that starts your car. The electrocytes, numbering in the many thousands, once stimulated by the neurological system, go through the same rapid, electrochemical switcheroo found in normal muscle or nerve cells, suddenly, almost simultaneously, reverse in polarity, and effectively generate an electric current that runs down the length of the organ and out into the surrounding water…all in a fraction of a second. In Electrophorus, the cumulative effect of all of these electrocytes discharging at once is extremely powerful…definitely strong enough to be used both for stunning prey (invertebrates and smaller fish), and for defense. If your butthole isn’t adequately puckered at the thought of that, note that adults can deliver a punch registering at upwards of 500 to 700 volts with a current of 1 ampere, which is enough of a shock to stop the heart of pretty much any animal on the planet sufficiently foolhardy enough to tangle with Electrophorus, something this predator found out the hard way. For some perspective, consider that if you could harness an entire Electrophorus discharge, you could power something like a hot plate or microwave. Or a decked out Christmas Tree.

So, electric eels, if sufficiently agitated by meddlesome humans, can potentially remedy the situation by replicating the exhilarating experience of shoving a knife in a household wall outlet, resulting in the perpetrator’s immediate demise. Death-by-eel is rare for humans, but it does happen, sometimes merely as a result of drowning after being blasted unconscious. Therefore, it’s advisable not to mess with Electrophorus, unless you think being found face down, floating in a swampy, Neotropical puddle, dispatched by a pockmarked fish that didn’t even touch you, seems like a dignified way to go.

Electrophorus may be the most famous, and dangerous, of the electric fish, but there are certainly many additional, possibly even stranger, species that receive little attention. And no, this guy isn’t among them.

A not-so-distant relative of the electric eel, found all the way across the Atlantic in tropical Africa and the Nile River, is the electric catfish (family Malapteruridae). Externally, malapterurids look like conventional catfish. Species range in size from about the length of your hand, up to the size of your leg. Many are dull brown in color, and sort of look like little smokies with eyes and tentacles.

Take THAT, appetite for breakfast tomorrow!

Its electric organ, derived from muscle tissue, lines the body cavity as a sheath, or (and I apologize for continuing with the breakfast meat imagery) a bit like a sausage casing. Using this organ, electric catfish of the genus Malapterurus can produce a discharge in the 300 to 400 volt range. This is enough of a wallop to discombobulate small fish for food, or to defend itself. The shock isn’t fatal to humans, but the jolt from a good-sized fish is guaranteed to be persuasive at getting you to let go of it pretty damn quickly.

These fish, and their electrical capabilities, were familiar to the people of ancient Egypt. Texts from nearly 5,000 years ago refer to electric catfish as the “Thunderers of the Nile”, and are among the earliest known acknowledgements of electrical phenomena. Smaller fish were used in a medical context, their shocks recruited for treating diseases of the nervous system like some sort of proto-electroshock therapy. Larger fish were wisely avoided; with them, it would more with the sizzling, and less with the salving.

Saltwater environments have their fair share of electric fishes as well. One inhabitant beneath the briny waves is the electric ray, also known as the “torpedo ray” or simply “torpedo.” They are different enough from other rays to comprise their own taxonomic order, Torpediniformes, one of the four major groups of rays (the others being skates, stingrays, and sawfish). The name of the group is not inspired by the naval weapon, but rather, the other way around. The “torpedo” device borrowed its name from a common genus of electric ray, Torpedo, in reference to the weapon’s ability to “stun” enemy ships. And by “stun”, I mean “sink.” The name of the fish comes from the Latin word torpere, meaning “numbed” or “paralyzed” (torpor…get it?). So, perhaps obviously, the ray’s name does not come from any physical similarity to an actual torpedo.

If we’re going by looks, I’d start with “black flapjack” for this guy. Or “punctured tire.”

Torpedo rays inhabit coastal waters the world over, and are ambush predators, shuffling their flat bodies underneath the sand and hiding in wait for prey. A brief zap and a voracious gobble and it’s over for whatever poor, oblivious bastard drifts by; a case of “shock and maw.” Unlike in electric eels and catfish, the electric organ of the torpedo ray exists as two, horizontally-oriented stacks of electrocytes on either side of the head. The electric discharge flows from the bottom of the ray’s body (the side with the mouth), up through the electric organ towards the top of the body and out into the seawater above…which is conveniently the “dinner arrival zone.”
Saltwater is more conductive than freshwater, so torpedo rays can get away with lower voltages (under 200 volts) in their discharges, but have somewhat higher amperages. Shocks from the largest torpedo rays (Torpedo nobiliana, pictured above, can reach the mass of a grown man) can be excruciating, but are not fatal to humans.

Like the electric catfish, torpedo rays are known from antiquity for their electrogenic properties and their use in medicine. Their role was mostly as a kind of anesthetic, since their shock would temporarily numb the patient. The Romans occasionally used them to treat headaches, and the ancient Greeks even used them to block out some of the pain of childbirth, because apparently that whole ordeal isn’t stressful enough for Mom without the experience of being smacked with slimy jump cables thrown in. It is unknown if any of the children were imbued with Magneto-like superpowers from the ray’s electricity…or powers like that kid in “Powder.”
The Greeks also employed the services of the torpedo ray in surgery, where it could be used as a localized anesthetic. Torpedo rays were evidently a lot like Flintstonian appliances in Greek society, electrocuting away the pain. Morphine? Try more-fin.

“Forceps, please…scalpel…fish.”

Another group of ocean-bound electric fishes are the stargazers (family Uranoscopidae). They live a life much like the torpedo rays, shallowly submerged in the sand on the continental shelf, hungrily awaiting prey to unwittingly swim by. They are squat-bodied monstrosities, with massive, forever-upturned faces (hence the name “stargazers”), primed and ready to strike upwards from the sand with their rapidly extendable jaws. Based on their frozen expressions, they also appear to be perpetually in a foul mood.

Your move, Grumpy Cat.

All stargazers are venomous, possessing two hollow spines behind the eyes to deliver the toxic cocktail when attacked…or accidentally stepped on by a soft, squishy, human foot. But, apparently this shit wasn’t impressive enough for a few species of stargazer, which have also evolved small electric organs derived from muscles in their damn faces. The shock put out by this turd-with-attitude isn’t much compared to the other fish previously mentioned, but it certainly helps stun small fish in that fraction of a second before the stargazer can shoot its toothy gob upwards to vacuum the unfortunate sucker in. It’s of no danger to animals as big as us, and run-ins with the jolt of a stargazer are more surprising than painful; less like grabbing a high-voltage fence and more like getting unexpectedly smacked in the chest with a basketball. For humans, its phaser is set to “stun.”

One species in the genus Uranoscopus even has a tag of skin on its lower jaw that it wriggles as a worm-like lure for small fish, getting them just close enough to electrocute and devour. This is kind of like advertising a garage sale, and then when the first curious visitor arrives at your house, you jump out of the hedges, zap him with a taser….and then eat him? Maybe it’s not a perfect analogy…

Bioelectrogenesis on the organismal scale has evolved multiple times in very different groups of fish, living in different parts of the world and in varied habitats. This “funneling” down into shared evolutionary strategies among independent lineages is a remarkable example of convergent evolution, and it was something that Darwin took care to note in his Origin of Species. From the cells of our most vital of tissues, to the beauty-deficient stargazer, to the genuinely deadly King of the Knifefish, the “spark of life” shares space with something far more literal. Life is an uncannily clever tinkerer, and bioelectrogenesis is just one spectacular representative of a great multitude of tools that have been intricately carved out by the tireless processes of evolution.

Image credits: Lightning, electric eel, electric catfish, surgeons, torpedo ray, stargazer

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Arachnids: Hooded Tickspiders

Hooded tickspiders.

Yes, I can sense the readers of this entry promptly throwing in the towel, giving up on life itself at simply reading the name of such a creature. Let the idea that Mother Nature is a nurturing, caring force be put to bed immediately, for evolution has crafted the cruel curveball that is the hooded tickspider; equipped with all the charm of a blood-gulping, parasitic tick, and the charisma and affability of a spider. Why even bother leaving the house at this point, what with such unholy, Dr. Moreauian amalgamations walking around? What’s next, cobra-tigers? Leech-sharks? Manbearpig?!

While it is certainly anxiety-inducing to contemplate an animal that seemingly exists as two highly-loathed arachnids essentially smushed together, as if done so to be an entry in a competition to generate the most unsavory Doritos Collisions flavor marriage of all time, in reality, this isn’t the case at all. Just as antlions are neither ants or lions, and dragonflies aren’t dragons, and aren’t really ‘flies’ either, the hooded tickspider represents a unique breed of creature, distinct from both ticks and spiders. Hooded tickspiders belong to a small order of arachnids; Ricinulei. There are about sixty species worldwide, making Ricinulei currently the least speciose order of arachnids, but more species are discovered as the years go by.

If you are breathing a sigh of relief as horrific imagery of web-weaving blood-suckers with no other mission than to patiently wait for you underneath the lip of your toilet seat peacefully leaves you, don’t get ahead of yourself. While hooded tickspiders are no threat to people (for a number of reasons related to their anatomy and extreme cryptic nature), they definitely provide enough innate, unnerving creepiness to make up for it.

Given the miraculous chance that you would encounter one of the few dozen species on Earth in the wild (which would inevitably involve you rooting around in the dirt and leaf litter for weeks in West Africa or the tropical Americas…because those are the only places they are found…and infrequently, at best), the hooded tickspider would probably yield more disappointment than colon-emptying terror. Truthfully, they aren’t much to look at if you aren’t familiar with what to look for. You won’t likely find anything even rivaling the size of the nail on your pinky finger, and they have all the brash coloration of a burlap sack. A captured, tiny, soil-caked hooded tickspider, curled into a defensive, ball shape, would be virtually indistinguishable from your common garden spider to the untrained, non-arachnologist eye.

However, if you were to take a closer look, you would quickly find that the pathetic, trembling critter in your hand appears to be missing something relatively important.
Like a head.

If this still-living animal were a vertebrate, and not an arthropod, you would probably be bounding off into the forest like fucking Ichabod Crane. But no, you, hypothetical, intrepid naturalist-person, know that arthropod nervous systems aren’t nearly as centralized in the head region as the nervous system belonging to cats, dogs, horses, and ourselves. Shit, cockroaches can live for weeks without their heads, in true Steven Seagal, “Hard to Kill” fashion. Perhaps that is what’s going on with this little guy? Maybe the head is nowhere to be found, but the body hasn’t caught on yet?

Well, that’s not correct either. It’s not so much that hooded tickspiders “took a little too much off the top” evolutionarily, it’s just that the “head”, or rather, all the parts associated with it, is obscured by a structure that is the origin of the first part of their common name. In the place where you’d expect to find head-bound organs found in the vast majority of normal, Earthling animals, there’s simply…nothing. Just a flat, exoskeletal plate. It’s like if your body was normal all the way from your feet up, but stopped abruptly at a goddamn manhole cover resting on your shoulders. This plate is known as the “hood” (and to arachnologists, the “cucullus”, which is Latin for “cowl”).
And of course, perpetually faceless, dark, hooded individuals are generally stand-up, good-natured characters. Nothing to fear at all.

So, the question becomes: what in the hell are tickspiders hiding under there? What secrets are they keeping from us? Well, you can sure as shit bet that it isn’t jelly beans or chocolate or anything remotely pleasant. Just like a manhole cover, this “cucullus” is movable, and if retracted reveals…not a whole lot, actually. The big “surprise” is a vacant mouth opening under there, along with a pair of chelicerae (mouth “parts” that are standard for all members of the subphylum Chelicerae) that end in sharp little claws, and that’s about it.
Hooded tickspiders don’t even have eyes, above or below the cucullus. But, despite being completely peeperless, they are highly sensitive to light, and likely achieve this capability through photosensitive cells placed laterally along their hard, outer cuticle (ancient, fossil species had eyes in these locations, but as hundreds of millions of years have gone by, the eyes appear to have been reduced). But as for discerning their immediate surroundings and navigating through their humid, forest floor world by way of light-based vision? Not happening. Hooded tickspiders blindly clamber along the leaf litter, fumbling around and feeling for any small insect or other critter in its path. It is then believed to snatch up the unfortunate morsel with its pair of small, delicate, claw-tipped pedipalps (the same appendages that have been modified into thick claws in scorpions), and then proceeds to stuff pieces of the hapless victim into its empty, butthole-like mouth. They are diminutive living tanks, half the size of the keys on your computer keyboard, yet covered in a heavy, air-tightly riveted together exoskeleton so extensive and impenetrable that it instead of a normally vulnerable face, it has a vault door. Like some kind of goddamn arachnid Death Star, it has a single observable opening, a tiny, tangible chink in its fortification…and even that is constantly shut up in the biological panic room formed by its “hood.” Up close, they look more like a human-crafted vehicle than a legitimate animal, appearing to simply be missing headlights and a grill.

Outside of the strange head region, the anatomy of members of the order Ricinulei is fairly normal compared to most arachnids. Sure, the exoskeleton is hard and super-durable, but the general body blueprint (sometimes referred to as a “bauplan” by biologists) fits the arachnid archetype. Cephalothorax (including head organs…or what remains of them), abdomen, eight pairs of walking legs…the works.
However, some elements of the 2nd and 3rd pair of legs are a bit odd in many species of hooded tickspider. For instance, the 2nd pair of legs is typically elongated, and leads far to the front when the animal is walking; it is thought that these legs act as sensory organs in a way, carefully guiding the animal by an acute sense of touch. The males of many species have even larger 2nd pair of legs, with hyper-muscular, comically bulky segments. These limbs may be used in male-to-male combat, where the two individuals would likely jostle with each other using them, perhaps trying to push the competitor aside or into a position of inevitable submission. This aggressive, competitive behavior is ubiquitous in the animal kingdom, and is observable in the clashing antlers of male deer, the brutal whipping of necks between male giraffes, and pretty much any weekend at a collegiate fraternity party when alcohol, in any amount, is consumed.

The 2nd walking limb morphology of males of this species (Pseudocellus chankin) has been described in the literature as “hella swoll, brah”

So, the 2nd pair of walking legs in hooded tickspiders tend to be modified, albeit in different ways and degrees, in both males and females. However, the 3rd pair of walking legs, in males, has evolved to carry out a very gender-specific function. In males, these legs end in a weird, fan-shaped cluster of nubby projections that form a scoop. During hot, hot hooded tickspider sex, the male uses these scoops like a lacrosse stick to cup and manipulate a spermatophore (a solid, gelatinous mass of sperm, basically; commonly used in arthropod reproduction, especially in arachnids), and then, once in position, lovingly crams it into her ovipore. So, it’s less like familiar, human sex and more like spackling a hole in a wall, but hey, apparently it’s been working for hundreds of millions of years just fine. You would be wise in pitying the female hooded tickspider, whose pinnacle of romantic experiences involves a clumsy, blind mate bumbling towards her lustfully, with fistfuls of his own spunk.

“…ladies?” *wink*

After a hasty copulation, and reception of the male’s seed fastball has occurred, the female lays a single, fertilized egg. This egg is then stored underneath the “hood” until it hatches sometime later, into a six-legged, soft-bodied larva that, over a surprisingly long amount of time, progressively molts into an eight-legged mature form. The intimate care that the female provides this single offspring represents a fairly rare parental tendency within arachnids, although it is similar to the motherly devotion to progeny exhibited by whip-spiders (something I examined in the first entry in this series on arachnids). Undoubtedly, carrying the egg in that tight area between the cucullus and mouth for so long is burdensome for the mother, and is a sacrifice that I would consider of evolutionary significance. It would be interesting to examine the long-term fitness consequences of the female hooded tickspider’s habit of stuffing their eggs underneath their face plates.

Fuck off, Easter Bunny. This hiding spot’s taken.

Perhaps the oddest thing about hooded tickspiders isn’t their outward appearance, but their strange legacy of discovery and their evolutionary history. The discovery of the order Ricinulei occurred in 1837 in England as a fossil representative from roughly 300 million years ago. It was originally misidentified as a beetle in the original literature, but it was soon revealed to actually be representative of a previously unknown group of arachnids. Only a year later, a living species was discovered in West Africa, making hooded tickspiders one of the few groups of animals on the planet who were first described through fossils of extinct species, and only later on observed still hanging out, alive, in the modern era (a more famous example of this situation is the coelacanth).
This is sort of the equivalent of suddenly discovering living Triceratops in some remote region of the tropics…except, you know, way less awesome.

As far as we can tell, Ricinulei is a very old group, dating back to at least 320 million years ago or so, and they’ve changed remarkably little since that time. As for their place in the arachnid family tree, two main lines of thought currently exist. The first is that hooded tickspiders are most closely related to the group containing mites and ticks (subclass Acari). This is based on similarities in early development (the six-legged larval stage is shared between tickspiders, ticks, and mites), as well as similarities in their mouthparts. The other competing hypothesis is that Ricinulei represents an old, still-surviving arm of a long-since extinct group of arachnids known as trigonotarbids. The order Trigonotarbida existed from about 400 to 300 million years ago, and was made up of arachnids vaguely similar in body shape to spiders, but with many plates (called “tergites”) running down the abdomen and no ability to produce silk. According to paleontological evidence, both trigonotarbids and hooded tickspiders had/have curious claws on the tips of their pedipalps, and a unique mechanism joining the two halves of the body is found in both groups, and exclusively so.

Wherever the hooded tickspider lineage comes from, there is no doubt that living representatives are among the oddest, and least understood, arachnids we have around. We are slowly learning more and more about these enigmatic little, faceless beasties, and we are continually revealing additional information about their strange life histories, diets, and origins. While I find them unavoidably fascinating, none of this makes them less unsettling, however, in my book. If you feel the same as me, and you fear your nightmares will inevitably be filled with armies of functionally decapitated, eight-legged, sperm-chucking, spidery demon-spawn after reading this entry, just let the following visual of Eowyn vanquishing a hooded menace play in your head as you peacefully drift off to sleep tonight.

Yeah. That’s the stuff.

Image credits: Opening hooded tickspider, Pseudocellus chankin

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Sea Spiders

Sea spiders.

I can already hear the exasperated groans coming from the readership of this entry. Sea spiders? Seriously? Why, arachnophobes the world over sigh, are spiders not content to just stay where they belong; many miles away from any potential interaction with my relatively exposed, swimming body? Need they go out of their way to ruin my summer vacation at the beach too? Why do there have to be marine versions of our creepy, spindly-legged friends, especially when we already have sea snakes, saltwater crocodiles, and what are the equivalent of massive “sea wolves” patrolling the briny depths? Perhaps, given the unsettling, lanky body shape of the sea spider, reminiscent of the daddy longlegs clustered in the dark, dusty recesses of our garages, it provides little comfort to say that these animals are not what their common name suggests.

In the same way that “sea cows” are not actually cattle equipped with flippers, and “sea wasps” aren’t really our delightfully sting-happy, land-lubbing acquaintances finding a new home beneath the waves (a nightmarish scenario if there ever was one), sea “spiders” are not simply spiders with water-proof webs and an appetite for calamari. They are something altogether different, belonging the taxonomic class Pycnogonida (meaning “thick knees”, perhaps referring to the shape of the joints in their segmented legs, or a cruel high school nickname for the group). This class is currently allied within the arthropod group known as Chelicerata, which does include arachnids; but, these “sea spiders” are, as previously mentioned, not arachnids themselves. However, even this classification may not provide enough recognition of the pycnogonid’s unique pedigree. There have been some recent studies (from both molecular genetics and evolutionary development angles) that suggest that sea spiders are not nested alongside arachnids at all, but instead are a part of a much older offshoot of the arthropod line…and are potentially the only surviving, highly-derived representatives of some of the first groups of arthropods to evolve (perhaps more closely related to enigmatic, extinct animals from more than half a billion years ago like Anomalocaris). If this is the case, then the pycnogonid lineage is effectively among the oldest animal groups on the planet.

Yes, no matter which classification assignment is correct, these critters occupy a unique branch on the great tree of life, and once someone takes a look at these pycnogonids up close, it becomes abundantly clear that these animals definitely deserve severely distinct classification, and have a tangibly alien quality to them. Seriously, pycnogonids are about as weird as it gets.

In case you haven’t noticed yet, I’ll point out that pycnogonids have incredibly long legs.

Less of a “body with legs” setup, and more of a “legs that have a body” situation, really

These absurdly elongated walking legs (which usually number in four pairs), combined with a comically reduced, skinny body, make the pycnogonid a curious sight to behold. While some species use these hair-thin limbs to swim by way of turning the leg into a paddle through the use of long bristles, often times, the legs function in the traditional sense, allowing these creatures to stride along the sandy ocean floor. But, despite being nearly entirely made up of legs, sea spiders are not swift like their terrestrial namesakes. The musculature devoted to locomotion is pretty damn pathetic, allowing only for slow, deliberate movements that are somehow both eerily robotic and graceful. Indeed, pycnogonids, with their cartoonishly proportioned bodies and cold, calculating progression across the open wastes of the abyssal sea, each step gliding unhurriedly forward without any hint of hesitation, they seem not only alien, but artificial. It’s easy to imagine them as mechanical automatons, marching silently across the pitch-black plains of the deep.

As if this notion of our oceans being inhabited by hoardes of robo-spiders didn’t need any additional reinforcement, consider the spine-tingling fact that pycnogonids don’t possess anything resembling a respiratory system. That’s right; no gills, no lungs. A respiratory system would likely be a cumbersome and unnecessary bit of visceral decoration inside that minimalist body of theirs. Pycnogonids simply absorb oxygen passively from the water that surrounds them via diffusion (the movement of molecules from high to low concentration), a strategy that is undoubtedly made possible by their bodies’ high surface-area to volume ratio. So yes, pycnogonids, in a disconcertingly similar fashion to the soulless, automated drones in any science-fiction flick, do not draw breath, in any form.

Their digestive system is also radically impacted by their bizarre body shape. The insides of the body segments (collectively grouped into a “cephalothorax”) of pycnogonids are apparently so cramped, that the digestive system has projections that extend into the tops of the walking legs. Pycnogonids are experiencing what, in humans, would be like wearing a corset so tight it made your intestines squirt into your thighs…inevitably resulting in a lifetime confusion between indigestion and Charley horses. Sea spiders are plagued by the pressure to fit “10 pounds of shit in a 5 pound bag”, and the evolutionary answer of having some of their guts wander out of their body cavity is made a necessity by the pycnogonid quirk of having a dramatically reduced abdomen (that big, bulgy segment at the back of arthopods like insects and spiders), which provides essentially zero auxiliary room for relatively important things…like organs. Pycnogonids end up cramming the equivalent of a house’s worth of belongings into a studio apartment, and they manage to achieve this by evolutionarily converting their innards into a game of Tetris.

The business end of the pycnogonid, the eating end, isn’t any less strange. The head of a pycnogonid is an obvious departure from that of its hypothesized closest relatives; the rest of the members of the subphylum Chelicerata (a brief overview of which I explored in this recent entry). The most glaring difference is that in place of paired, mobile mouth parts (such as those found in arachnids and horseshoe crabs), the main tool used to procure food is a proboscis, which manifests as a trunk-like appendage that in some species is short and squat, but in others is a monstrous organ possessing a shape somewhere between that of a bowling pin and the nose of that giant Muppet, Sweetums. Accompanying the proboscis in the head region, are typically three pairs of appendages distinct from the walking legs; they are the chelifores, palps, and ovigers. The chelifores and palps are more actively involved in gripping and manipulating food items, while the ovigers, placed furthest back on the body of the three pairs, is more heavily involved in reproduction. Ovigers, usually the longest appendages outside of the legs, and found folded up underneath the body, are often used in courtship displays and for cleaning the exoskeleton. It is the pycnogonid male that carries and cares for the fertilized eggs, tucking them underneath the body and using the ovigers to ball the eggs into two large, globular clusters. This gives the animal the appearance that it is wearing white mittens and then sticking them in its armpits. Allowing for the sea spider to survey its world, perched on top of the cephalothorax, near the head region, is an eye turret (called an “ocular tubercle”) that houses four simple eyes.

Most species of sea spider are exclusively carnivorous, and either take live prey or scavenge it off the ocean floor. The proboscis, which can occasionally have spines or teeth arming the lips at the tip, is employed as the pycnogonid weapon of choice when dining. Commonly, they will feed on big, stationary, soft creatures like segmented worms, sea anemones, and sponges by stabbing their proboscis into the side of these animals. Then, aided by a cocktail of digestive enzymes streaming out of the proboscis, the sea spider slurps up a hunk or two of delicious tissues directly into its gut, and then gets the hell out of there to move on to the next sorry schmuck on the seabed.

Wanted: for a suck-and-run

If the idea of being leisurely stalked by a pycnogonid and aggressively pierced by nature’s meanest variation of the bendy straw is keeping you from going snorkeling anytime soon, then you should reconsider. Firstly, pycnogonids, creepy as they are, do not view humans as food, and probably couldn’t do any damage with that Gonzo schnoz even if they tried. You’d be more likely to drown from getting entangled in seaweed, than to receive even the slightest pinprick from the proboscis of a sea spider. This reality is enforced by the diminutive size of the vast majority of pycnogonid species. Most pycnogonids you’ll observe in the wild are small as shit, with leg-spans only stretching as wide as the nail on your pinky finger. These characteristics make our alien, arthropod friends pack as much deadly force as a wind-blown dandelion seed.

However, exceptions to the rule abound in the natural world, and in the case of pycnogonids, it is size. While most of the 1,300 or so species of sea spider are found in shallow waters near shore, and are quite tiny, there are a small number of species found in the coldest parts of the ocean that are comparatively gigantic.

Looks like even the ruler is afraid to get close

Meet the aptly-named Colossendeis, a genus of pycnogonid that has representative species in all oceans of the world. However, it is in the icy waters surrounding Antarctica that some species, like the one above, possess such massive bulk. The largest species of Antarctic giant sea spider have leg-spans as wide as a trash can lid and proboscises as long as your finger. This significant increase in size compared to other sea spiders fits into two phenomena effecting marine invertebrates; polar gigantism and deep-sea gigantism. The latter of these two has been documented to occur across many groups of organisms in the deepest parts the ocean, where inhabitants of the abyss are many times larger than their shallow water relatives; examples include cat-sized, scavenging isopods (relatives of terrestrial “pill bugs” or “roly polies”), and the numerous varieties of giant squid. Explanations for this phenomenon have been offered over the years, and one prominent hypothesis is that the cold waters of the deep encourage an increased life-span, and in the case of many invertebrates (which tend to grow continuously throughout their lives) this results in a much larger adult size. This reasoning would also be consistent with polar gigantism, in which species of marine invertebrates in cold polar waters, at any depth, also exhibit an increase in size compared to their closest, lower latitude relatives. The giant sea spiders of the Antarctic are both found in deep water, as well as the still quite cold surface waters, and are thus candidates for both described tendencies. Of course, despite their intimidating size, even Colossendeis sea spiders are benign animals.

“Unhand me! Now! Or I shall lightly poke you with my proboscis and tickle you with my legs!”

Pycnogonids may look like someone took a spider, starved it, gave it a shiny coat of monochromatic paint, threw it in the ocean, and made it walk backwards…but they are, in reality, a fascinating group of animals with few relatives. Pycnogonids are something of a staggeringly old taxonomic island, a distinct offshoot existing for several hundred million years. There are more than 1,000 modern species, but we don’t know as much as we’d like about them, and we are just now starting to get a grasp of their ancient evolutionary history through the fossil record and genetic studies. In time, we may be able to unlock some of the pycnogonid’s mysteries, and get an even greater appreciation for the slow, silent, stilt-walking figures that have been pestering sponges and anemones the world over since before the Age of Dinosaurs, and will hopefully continue to do so for eons to come.

Image credits: Opening sea spider, red sea spider, striped sea spider, Colossendeis, held Colossendeis

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Arachnids: Amblypygids


Yes, arachnids; our eight-legged “friends” that cling to the shadowy, forgotten corners of our homes, under the damp seal of a rock, to the harsh, hot crust of the desert, and to their feathery webs, crafted overnight in our gardens. Arachnids, as a group, are not at all unfamiliar to us humans, and while, overall, the relationship between ourselves and these ubiquitous invertebrates is a bit complex, by and large in Western culture, arachnids are feared and reviled. The most familiar groups of arachnids, spiders, scorpions, ticks, and mites, have earned reputations as some of the most terror-inducing, retch-provoking, and spine-shuddering animals we encounter in our day-to-day lives. We cringe at the thought of ticks embedded in our skin, face first, bodies inflating into pulsating balloons of blood. We attempt to ignore the unsettling fact that millions of microscopic mites graze on our dead skin cells, both separated from our bodies and still attached. We regard scorpions, prehistoric beasts made of plates, claws, stingers, and venom, as symbolic of the uninhabitable desert wilderness.

And then, of course, there are the oh-so common spiders, creatures who receive reactions from humans ranging from praise for their beautiful, radial web architecture, to mild annoyance when encountering a surprise face and mouthful of this same web on a forest trail, to revulsion and a swift, life-ending blow with a shoe or newspaper (turning the hapless critter into a drab smear of entrails), to blinding, full-on arachnophobic panic. These last group of arachnids, in particular, are the animal kingdom’s ‘black sheep’ in our culture, becoming a fixture in our conceptualization of the spooky atmosphere of Halloween; curiously, along with bats, spiders are among the few living, non-fictional entities we set alongside the stereotypical ghoulish folklore characters like zombies, skeletons, witches, and sundry other monsters. Apparently, we consider spiders among the creepiest, darkest, and most unnerving of all living things.Those that fear spiders, and creepy-crawly arachnids in general, cite these creatures’ long, spindly limbs, soul-less eyes, hairy bodies, venomous fangs, fast movements, and a tendency to inhabit abandoned, abyssal areas where we are already at unease, as some the reasoning behind their prejudice. This instinctual aversion is strong enough, and prevalent enough, to inspire scores of films and literature where spiders are featured as agents of terror. Seriously. There are plenty. Of examples. Our overwhelmingly negative view of spiders, especially, obscures some of their talents, many of which are immensely useful to humans. These include the production of a silk that is tougher than Kevlar (which has instigated research into super-strong materials), and an inarguably critical ecological role that keeps populations of their prey items (insects) in check. Spiders, like most arachnids, in the immortal words of Rodney Dangerfield, “get no respect.”

Oh jeez. Are you guys happy now?

In the same way that spiders and other more familiar arachnids are misunderstood and have unrecognized, underappreciated roles in our lives, the very definition and realization of what arachnids, in the broadest sense, actually are typically is met with limited experience and knowledge. For example, most people, if prompted to “name an arachnid” would answer firstly (overwhelmingly so) with ‘spider.’ Some might follow up with ‘scorpion’, or perhaps ticks and mites…pretty much everything with eight legs and without insect-like antennae that comes to mind. However, the diversity of arachnids extends far beyond the web-bound orb weaver bobbing in the breeze in your front yard’s hedges, or the chigger causing lovely, itchy welts to form on your skin. While these groups are the most speciose, and most common accompaniment to our daily lives (good or bad), there are entire taxonomic orders of arachnids that go quite completely, and miserably, ignored.

This entry is to serve as the first in a series of explorations into the less-loved (or, perhaps, less-persecuted, simply out of unfamiliarity) arachnids.

But first, perhaps it is helpful to start with the following question: what is an arachnid, exactly?

The rule of thumb distinction between insects and arachnids, when trying to broadly identify a little, buggy critter with lots of legs, is the number of limbs, the number of body segments, and the presence or absence of antennae. This diagnostic method tends to work well in practice, but it doesn’t really inform why this distinction between the two types of animals is important, and the phylogenetic, evolutionary context.

Firstly, arachnids are members of the phylum Arthropoda (meaning “jointed leg”). Essentially everything you find on this planet that has an exoskeleton, jointed appendages, and a segmented body is an arthopod; think insects, crabs, centipedes, shrimp, and the extinct trilobites. As far as animals are concerned, the vast bulk of them, both in number of species and number of individuals, are arthropods. There are over a million described species. If you were to randomly select a single species of animal on this planet, four times out of five that species would be an arthopod. When most people think of animals, furry mammals and other vertebrates instantly come to mind, but in reality, Earth is fucking covered in a tide of tiny, robot-like arthopods in all environmental realms.

Within this phylum are subdivisions, called ‘sub-phyla’ that break up the gargantuan number of arthropod species into about four living groups. One of these groups is the Chelicerata, which includes arachnids, but also includes living fossils like horseshoe crabs (obviously not true, crustacean crabs) and potentially an enigmatic, alien group of animals known as “sea spiders” (although the classification on this group is constantly in review). It is the arachnids that make up the great majority of chelicerate diversity. Chelicerates are distinguished by the presence of unique pre-mouth appendages known as chelicerae, which have diversified into a wide range of morphologies, including the fangs of spiders, and pincer-like forms in most other members of this clade. Chelicerates also have appendages called pedipalps, which in more primitive groups are leg-like, but in “higher chelicerates” have been modified into delicate sensory tools, organs used in reproduction, or weapons for defense or procuring food. Pedipalps can, with some reservation, be thought of as the chelicerate version of hands. Tiny, finger-less, hairy, creepy, jointed hands.

Arachnids, members of the class Arachnida, are the most prominent chelicerates (with more than 100,000 species), and have become by far the most successful group of chelicerate to colonize terrestrial ecosystems. This group, more or less, has two distinct body segments (called “tagmata”); a cephalothorax (essentially the fusion of the head and thorax, typically covered by an unsegmented carapace), and the abdomen. The separation of these two tagmata can be stark, like in spiders, or more nuanced, like in ticks or scorpions.

Not labeled: Horror genre marketability gland

The distribution of internal organs, and relative position of limbs, in this bi-segmented set-up that the arachnids have going on is a little hard to understand from our own vertebrate perspective. Imagine if you didn’t really have a neck, and your head sort of just continued on into your body, and if your arms and legs attached in this area right behind your head. Now, imagine if everything sort of pinched off behind your legs, and about 90% of all your major organ systems were packed into a bulbous mass sticking out beyond that “waist” behind your head-legs. Oh, and you wouldn’t really have a “normal” circulatory system, just a blood-filled cavity that sort of periodically dumped oxygenated blood on the other organs. This is known as an ‘open circulatory system’ and is typical of arthropods.

You’d be a horrific, human calabash…with limbs…and a hole leading to your lungs where your asshole should be. Your actual anus would be on your lower back, right above your respiratory hole. So, holding your breath while taking a dump would be recommended. As if that wasn’t bizarre enough, under this configuration, you would have your genitals positioned on your sternum. You would probably find it hard to get a date.

Arachnids certainly don’t eat like we do either. The overwhelming majority of arachnid species are carnivorous, and tend to liquefy their prey items by injecting or covering them with digestive enzymes after capture. Only in a small minority of groups is the viscera-smoothie option rejected for the consumption of conventional, solid bits of food.

Reproduction and early life development in arachnids differs significantly from that of insects. Most of this difference comes in the lack of any kind of metamorphosis taking place in the development of young arachnids. Once arachnids are out of the egg, there’s no time for legless, lackadaisical, larval childhoods; they get right with the program and are born with the capacity for rapid movement (and within a short amount of time, the ability to kill food for themselves), being simply small, softer-bodied versions of adult arachnids. Anyone who has come across a mature spider egg sac and poked it with a stick is well-acquainted with the precociousness of hundreds of miniature, ghostly white, pollen grain-like babies, which quite suddenly engage in an exodus from their safe nursery…and onto the stick…and onto your hand.

Of those 100,000 arachnid species, 40,000 are found in the order that contains the spiders (Araneae). Another 30,000 are in the order belonging to mites and ticks (Acari). There are another 2,000 species of scorpion. Three-quarters of arachnid diversity is taken up by these three groups, but there are roughly a dozen orders within the arachnid class, and most of those remaining nine groups have species counts in the low hundreds, and don’t nearly get the publicity or exposure as a common barn spider or a deer tick.

The first of these neglected orders that will be addressed is the order Amblypygi, with its comparatively meager 136 described species. Pronunciation of this order’s name may conjure imagery of a sauntering swine, but the translation from Greek derives its true meaning…which is quite literally “blunt ass” (amblyo- = dull, blunt, pygo- = rump). It seems like an oddly benign descriptor for an arachnid, especially when it’s for the entire taxonomic order. Perhaps, you think, it’s a stumpy, adorable sort of thing; the rare ‘cute’ arachnid. Surely, you say, that’s what the “blunt butted” Amblypygi must consist of.

You were wrong.

This unholy combination of legs, spines, and the tears of small children is known as a ‘tailless whip scorpion’, as well as a ‘whip spider’, although it is neither a scorpion or a spider and is obviously far more terrifying than either of those things. This twisted creature appears to be molded out of the most unsettling portions of spiders, praying mantises, crabs, and daddy longlegs, but through the curious gestalt properties, is a uniquely hideous product of nature. You may recognize these animals as the “spider” that was used in demonstration of the “three unforgivable curses” in this scene in the film adaptation of “Harry Potter and the Goblet of Fire”…or, alternatively, in the worst dream you’ve ever had.

The ‘whip’ part of the name comes its first pair of legs, which have been modified into elongated, highly-sensitive, antennae-like probes. It is tempting to hypothesize that the function of these whips is for tickling the nose of sleeping humans so that they’ll open their mouths, allowing for this charmer to climb inside and lay its eggs in the back of the throat… but this is, fortunately, not the case. The whips are instead sensory organs, held far out in front of its body in order to detect anything worth snatching up for a meal. This includes crickets, beetles, caterpillars, and firstborn Egyptian sons.

It achieves this by use of its pedipalps, which you may have noticed have been modified into vicious, raptorial claws (“raptorial” typically referring to a limb that has underwent modifications for grasping prey). These long pedipalps, whose ends are densely studded with sharp, interlocking thorns, are kept tightly folded up against the gnashing chelicerae of the amblypygid, patiently awaiting some incredibly unlucky insect to cross its path. The pedipalps are also used in territorial displays against others of the same species, and amblypygids routinely extend and clash them against those of a transgressing individual (like bucks do with their antlers) in order to persuade them to step off their turf, whether their neighborhood is rich in mates or in prey.

That sound you’re hearing is your bladder involuntarily emptying itself.

However, unless you are living in the tropical and subtropical regions of the world, you are unlikely to come across an amblypygid. Even if you were a resident of these warmer latitudes, you’d still have to search for these guys. They are usually nocturnal creatures, preferring to wedge their flattened bodies underneath wet logs, stones, or a piece of tree bark during the day…places where you really shouldn’t be putting your hands anyways while in the tropics. At night, they move silently and carefully along the rainforest floor, surveying their world by way of the delicate touch of their sensory legs. This is really the only way for them to interact with their environment, because amblypygids are really fucking blind. This may be a little surprising, considering that they have eight eyes; three grouped together on each side of the cephalothorax, and two more right in front on that raised bump that looks a bit like a nose.

If you were to somehow come across an amblypygid in the wild, you would have little to worry about. I can hear your incredulous gasps now, “What? How can this be? Look at this thing!” Amblypygids generally resemble what would come skittering out from between the dank, unwashed folds of a nightmare. They look like the voracious guardians of an ancient, booby trapped tomb in an Indiana Jones movie, or something that would hitch a ride across the galaxy on an asteroid, only to collide with Earth, scuttle out of the impact crater, and seek to take over the planet. If there was an organism banished to inhabiting the dark, dusty, cramped, lonely unknown of the area behind your washing machine, it would be an amblypygid. Surely, you protest, this spindly troglobitic creature, with its horrible claws, beady eyes, and all-feeling whips, bound to darkness and the humid, alien, subterranean world just below the forest undergrowth…must be deadly. Indeed, it must be a rabid, bloodthirsty monster; fangs overflowing with venom, legs taut with the anticipation of leaping and clinging to your face, spiky pedipalps itching to spring wide open and impart a puncturing embrace.
While the imagery of a company of ill-fated cave divers being feasted upon by hoardes of hyperaggressive, dinner plate-sized demon-spiders might seem appropriate for an animal as unsettling in aesthetics as the amblypygid (or for a low-budget, made-for-TV thriller; I’m looking at you Syfy)…but in reality, this scenario is an impossibility.

Observe, the horror that is an interaction between a human and a large amblypygid:

The person handling the amblypygid in the video above is by no means brave (so stop being impressed). The truth is, amblypygids are about as harmless as it gets for an arachnid. Their chelicerae are not the hollow, venom-engorged tubes found in the spiders, and the most danger to a human that comes from an amblypygid nip is a small amount of transient pain; like a mosquito bite with less itching. Just getting an amblypygid to engage in such behavior requires a great deal of pestering, as these creatures uniformly flee and seek refuge in tight, hard-to-access areas at the first annoyance. Defensive retaliation, a very rare occurrence, usually takes the form of a strike with those prickly pedipalps. This is kind of like getting smacked with a nail-bat…but with one only a couple inches long, probably doing about as much damage as a light brush with a thorny blackberry vine. Put simply, if an amblypygid decides to be uncharacteristically feisty with you, I’m pretty sure you’ll live.

Because of their docile temperament, combined with their intimidating appearance and size (some species can have leg-spans significantly wider than a human hand) amblypygids are reasonably popular as pets. Many other similarly-sized arachnids, like tarantulas and some larger scorpions, have a very real capacity to do some harm if handled improperly and/or given the opportunity to become aggressive. For example, some species of tarantula (only found in the New World), if threatened, will take a hind leg and quickly rub the top of the abdomen, kicking up a cloud of urticating hairs. These tiny, barbed hairs are incredibly irritating to human skin and mucous membranes, and if inhaled can cause potentially dangerous levels of airway inflammation; if the sharp hairs get embedded in the eyes, there is a substantial risk of partial or temporary blindness. Tarantulas can also plunge those giant fangs into human flesh as a defense mechanism, although this is rare. Unlike a nibble from the weak chelicerae of an amblypygid, a tarantula bite is not a walk in the park. You won’t die or get sick from the venom, but the sensation is a bit like being stabbed with a freshly sharpened pencil…on fire. Also, in the days following, the area of the bite swells up into a tender bubble of misery.
Scorpions, of course, have a whole suite of painful/deadly tools they can use on humans that I don’t think I need to go over.

Amblypygids easily achieve the ‘wow’ factor held by these other common arachnid pets (and then some), and bypass all of the risk of harm or death associated with ownership and handling.

We tend to view arachnids, and other exoskeletal, creepy-crawlies, as unthinking, anti-social automatons whose only function is to eat, avoid being eaten, and to make more of themselves. Often times, this assessment is somewhat accurate. Hell, the female representatives of many arthopod species (like spiders and praying mantises) routinely wolf down their bite-sized lovers without even batting a compound eye…because apparently that’s your only available post-coitus activity if you’re smaller than a cigarette. Some insects, like ants, termites, wasps, etc., form highly hierarchical societies and massive colonies of interdependent individuals, but this is an exception to the general rule in inter-arthropod relations. Tending to and caring for offspring beyond the egg stage isn’t  a standard behavior, and communication between mothers (I say ‘mother’ because ‘father’ is probably currently in the process of being digested by ‘mother’) and offspring is certainly limited. Let me put it this way: “good parenting skills” in arthropod households typically consist of refraining from immediately eating more than half of your hatchlings…and that’s about it. There’s no way to get around it; arachnids and other arthropods are a cold, sociopathic bunch.

It may surprise you, given their off-putting, emotionless exteriors, that amblypygids are among the most socially savvy of all arachnid groups. Beneath that stiff, hard exoskeleton, amblypygids are, both literally and figuratively, big ol’ softies.
While allowing newly-hatched young to piggyback for a little while is found in some arachnids (scorpions and some spiders do this, for example), the amount of care and interaction that amblypygids give their relatives is unusually high by arachnid standards.

One-upping soccer moms for 400 million years

Research from entomologists at Cornell a few years back on two species of amblypygid revealed that familial interaction in these arachnids might extend far beyond simple motherly protection and transport for squishy newborns. For example, mothers in these species keep their young (I like to call them “amblypyg kids”) close by long after they were able to fend for themselves and get around on their own. Throughout the young’s pre-adult development, their mother caresses them with her sensitive whip legs, and the young reciprocate with their own sensory appendages. The young also interact with each other in this way; constantly petting each other with their whips. It’s as if they do this to soothe each other.

Yes, the scary, nasty-looking amblypygid is a cuddler.

Perhaps most strikingly, the young siblings of these species organize themselves into social groups all the way until reaching sexual maturity, which then immediately leads to combative, aggressive behavior towards each other. Anyone who experienced their teen years with siblings can probably identify with this phenomenon.
Up until this developmental stage (amblypygid puberty occurs roughly a year into their lives), the bonds formed between siblings and their mother are steadfast. If scattered and dropped into unfamiliar territory, the siblings feel around and seek each other out until they all re-group into one, big, happy family again. Of course, once the gonads kick into gear, family reunions result in unrepentant cannibalism. But, until then, brotherly and sisterly love are plentiful in an amblypygid’s world.

So, this concludes the introduction into one of the less acknowledged and less understood orders of arachnids. Despite their appearance, you certainly can’t judge amblypygids by their cover. For all their demonic homeliness and menacing first impressions, amblypygids are among the most amorous of the class Arachnida, both towards giant primates like ourselves, and uniquely towards members of their own brood. Perhaps if an animal with a brain smaller than a period on this page can learn to care for, and appreciate, other individuals in its species, we can somehow manage to do the same.

Image credits: Opening spider photo, source for arachnid diagram, Amblypygid #1, Amblypygid #2.

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Evolutionary Anachronisms

The avocado.

You may think you have a good relationship with the avocado. The buttery fruit of this plant may regularly accompany your turkey sandwich, sliced and fanned out across the bread. Or, it may serve as a hearty dip in the form of guacamole. More recently, avocado is seemingly being utilized in a greater variety of ways, being deep-fried, thrown in macaroni and cheese, and finding its way onto burgers, Subway sandwiches, and even into ice cream. You’d expect that with all this attention, our green-fleshed, knobby-skinned friend, the avocado, would be content with its current role in human culinary efforts.

However, the avocado may very well be lonely.

Despite all our affection, this loneliness stems from the avocado potentially having eyes for another. I mean this, of course, in the sense of the concept of co-evolution (which I examined in a previous post), which is directly tied to the reproductive role of the fruit itself. The main function of a fruit (a botanical fruit, typically meaning the structure derived from the reproductive tissues of the flower housing the seed(s)), is to move seeds away from the parent plant and into areas that promote growth and survival. Many types of adaptations in fruits exist to help achieve this goal of seed dispersal; from the wind-catching dual blades of maple tree fruits (known as samara), to exploiting the appetites of the ubiquitous (and notably mobile) animals in the neighborhood. This latter evolutionary strategy involves the development of fruits that enrapture animal taste buds and provide irresistible caloric value, allowing consumed seeds to travel safely inside the gut of an unwitting, far-traveling chauffeur until being excreted away from the crippling shade of the parent plant. This is called “endozoochory.”

Most endozoochorous fruits have evolved to be eaten by fairly specific animals. Predictably, fruits adapted to be taken by songbirds are going to have different physical attributes than those associated with insects or elephants. You can try and fit a peach pit through the body of a sparrow, but you aren’t going to get very far. Similarly, expecting tiny, thin-walled seeds to withstand an elephant’s battery of grinding teeth isn’t realistic either. The suite of fruit traits evolved for dispersal by a given group of animals roughly categorize into “seed dispersal syndromes.” By interpreting these syndromes, we can often get a good idea of what the primary dispersing animal, the other partner in a co-evolved relationship, is likely to be.

In light of this, it becomes obvious that despite our love of the avocado (specifically, domesticated cultivars with lots of flesh; wild avocado fruits have a thinner layer of green deliciousness surrounding that pit), it is not “meant” for human consumption and seed dispersal. Any attempt to chew up the whole fruit and swallow the massive pit is bound to land your asphyxiating ass in the cemetery. However, the situation for avocado’s seed dispersal isn’t much better in its wild Neotropical range. Many smaller animals (like monkeys) that partake in avocado consumption are “pulp thieves”, ingesting the oily layer and tossing the seed at the base of the parent tree. In fact, no native animal is known to consistently and effectively disperse wild avocado. Why then does the avocado make a big, energetically expensive fruit that doesn’t cut the mustard on dispersal? Also, who is the true “buyer” of avocado’s product?

The answer to both those questions may be that the avocado’s chief dispersal agent is extinct. Kaput. Gone. Effectively an “ex-animal.” This would mean that the avocado fruit is an evolutionary anachronism, equipped with traits fine-tuned by evolution for interaction with a species that has quite suddenly disappeared, leaving the once perfectly capable seed vessel under-appreciated and inadequately used.

“Fruit’s almost ripe, guys. Come and get it! Hello? ….Guys?!”

It’s a very serious case of being all dressed up with nowhere to go.

The ideas of a “megafaunal dispersal syndrome” (megafauna referring to beasties people-sized and larger) and evolutionary anachronisms have their genesis in the research of Dan Janzen, whose observations of abandoned piles of giant, tough fruits all over the Neotropics first sparked thoughts of the elephant-like (and recently extinct) gomphotheres acting as the proper seed vehicle. The theory is a fascinating departure from how ecological interactions and adaptations are typically thought of, and it has been met with opposition from within the discipline over the past few decades.If these megafauna-plant anachronisms do indeed exist in nature, recent paleontological events have certainly provided quite the opportunity for them to develop. Earth experienced a catastrophic loss of megafaunal biodiversity over the last few tens of thousands of years. In the Americas, it happened particularly recently; only about ten thousand years ago. If you go back just half a hiccup in geologic time, the New World was quite a different place, and was awash in very large numbers of big, furry critters. Megafauna like camels, mastodons, mammoths, rhinoceroses, horses, gomphotheres, and giant ground sloths strode across North America from Oregon to the panhandle of Florida. In South America, tank-like glyptodonts (huge cousins of armadillos) and an odd, extinct group of hoofed animals called notoungulates dominated the landscape. They were all gone by about eight thousand years ago, leaving behind ecosystems abruptly impoverished of the ample appetites of bulky mammalian bodies. Given this prehistoric context, imagining the nutritive avocado sustaining elephantine mastodons or gomphotheres up until their sudden demise, leaving the avocado to “catch up” evolutionarily, may not be much of a stretch. Or perhaps the avocado found a home in the bowels of another animal, like the towering ground sloth, Eremotherium, which weighed more than a UPS truck and could reach nearly three stories up into the trees with its clawed forelimbs.

Ground sloths: evolution’s answer to construction machinery

Over the years, as the idea spread, other candidates for evolutionary anachronisms were proposed (a significant proportion of which are outlined in author Connie Barlow’s comprehensive examination of the theory in her book, “The Ghosts of Evolution”).

A fairly extreme example might be found in a plant native to a small area of the south-eastern U.S., the osage-orange (Maclura pomifera). The plant has been spread across the continent by humans seeking its unique utility as fence post material, but without human intervention, osage-orange is miserably shitty at seed dispersal. It produces a Nickelodeon slime-green, brain-like fruit the size of a softball, which is full of runny latex that is an industrial adhesive-level of sticky, and nothing in nature, including domesticated animals, seems to have much interest in touching the stuff. This means that the fruit, after falling, is staying put, save for a slight downhill roll or a kick from a frustrated park visitor. This results in the fruit piling up underneath the tree and densely adorning the ground as if a nearby tennis ball factory had exploded.

Fruit not falling far from the tree, and not being able to do a damn thing about it

Without its hungry, hairy “partners in time” around to gobble up these succulent globes, Maclura pomifera may be at the mercy of gravity and the swift onset of rot.

Another oft-cited example of anachronism that might be familiar to many readers is the honey locust (Gleditsia triacanthos), a common ornamental species found in city parks. The plant, being in the legume family, produces long, multi-seeded pods as fruit. However, these are no diminutive pea pods; the gently spiraling fruit of honey locust can be as long as your forearm. The honey locust has evolved big fruit that requires a big mouth to take it in without seed loss…a big mouth that no longer exists in its native North America. Cattle and horses will eat the pods off the ground, and assist in dispersing seeds that way, but it’s been offered that perhaps a high-reaching Pleistocene browser, like a mammoth or long-necked camel, is the plant’s intended target.

Anachronistic traits may not be restricted to just fruit. Many plants have evolved armaments (spines, toxins, etc.) as deterrents to overzealous browsing by herbivores. Honey locust is no different, being equipped with pencil-thick thorns encircling the trunk and branches. These sharp-as-hell, dense clusters of thorns are ridiculously excessive for modern browsers like deer, and occur on the tree far above their reach. They seem to do little else these days but strongly discourage tree house construction, crushing the dreams of children everywhere.

This is not a climbing tree

In Pleistocene Arkansas, these lovely daggers would have been “persuasive” tools against the tender trunks, tongues, and lips of much larger creatures, who may have been eager to strip the tree of its precious foliage (perhaps as a side dish to those crunchy pods). Honey locust may be somewhat of a Hiroo Onoda; the war’s been over for a while, hungry mastodons are no longer a threat, but the plant isn’t laying down its arms.

Anachronistic situations have been proposed outside the plant kingdom as well. Consider the pronghorn (Antilocapra americana), native to the open areas of the American West. While commonly referred to as the “pronghorn antelope”, it is not at all an antelope, and is the last remaining species in the family Antilocapridae, a group of mammals closely related to giraffes that once enjoyed great diversity in Pleistocene North America. Pronghorns also have the distinction of being the fastest land animal this side of the Atlantic. I mean, these things can move. A spooked pronghorn can easily break the 55 mph speed limit on the rural roads that criss-cross its habitat, and hold that pace for half a mile. Such speed is an obvious adaptation for predator evasion, but in modern North America, it far exceeds the requirement for outrunning comparatively sluggish layabouts like wolves and cougars. Like the mammoth-puncturing thorns of the honey locust, perhaps the reason comes in the form of a dearly-departed influence.

John Byers, a zoologist at the University of Idaho, thought so, and suggested that the living Ferrari that is the pronghorn owes its unreal get-up-and-go to ancestral predation by the American cheetah (Miracinonyx). Yes, a goddamn cheetah. North America was once home to a pants-shittingly diverse collection of big cats, including American lions, saber-toothed cats, and Miracinonyx, which wasn’t a Yankee version of the African animal, but a relative of the cougar that converged on the same “savanna rocket” hunting strategy. Miracinonyx was the lithest cat in town, meaning that if there was ever a selective pressure favoring blazing speed in antilocaprids, this guy was the whirlwind of muscle and claws behind it. Nothing gets the lead out of your species’ ass like the culling power of teeth with turbo boosters. Now, thousands of years later, Miracinonyx is no more, and the pronghorn hasn’t yet caught on, evolutionarily. Its accelerator is stuck to the floor, and will remain that way until the “need for speed” is sufficiently challenged by the “need to breed.”

If your ancestors recently put up with cheetahs, you’d be pretty fucking alert too

Additional suggested anachronisms abound, ranging from familiar fruits like papaya and prickly pear, to the idea that unique plant growth forms in Madagascar and New Zealand evolved in response to pruning by extinct flightless birds like moas and elephant birds.

Evolutionary anachronisms are likely tenuous, passing phenomena. Energy-sapping waste tends to be efficiently cropped out by natural selection, and those species that cannot transition quick enough into the new ecological context, will inevitably follow their extinct partners into the permanence of extinction. Indeed, proposed anachronistic plants are often clinging to existence, tending to be rare with patchy distributions (many times associated with unfortunately competitive river floodplains, since their uneaten fruit rolls or floats into these lowlands). Imagining great beasts munching on gooey osage-oranges, or crunching dried honey locust pods, is a wonderful thought-experiment. But, in addition to this, perhaps we should consider, if evolutionary anachronisms are a common side-effect of extinctions, how many temporal upsets we are generating as a result of the on-going, human-driven mass extinction.

Image credits: Sliced avocado, hanging avocado, Eremotherium, osage-orange, honey locust thorns, pronghorn.

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Metatherians (Part 2 of 2): Odd Living Representatives

…so, some more about those metatherians/marsupials.

In the previous part to this two part series, I went over some of the now-extinct metatherian megafauna that once graced Australia and South America. These animals were fantastic and marvelous pinnacles of metatherian specialization, yes, but there are plenty of surviving metatherians, all of them of the ‘marsupial’ clade, that are also largely ignored and their lives obscured. There are some truly bizarre and amazing marsupials outside of the traditional koala/kangaroo/wombat/possum group that essentially everyone on the planet associates with the marsupial infraclass, and all of them somehow survived invading hoardes of humans and other placental species (although, in most cases, just barely).

But, perhaps it’s best to start with answering the question of just why it is that marsupials have been, time and time again, outmatched by placental counterparts. The great metatherian reign over the past few tens of years was a phenomenon restricted to the isolated island continents of Australia and South America, and as soon as placentals came into these areas (via the Isthmus of Panama from North to South America, and through humans using the Ice Age land bridge from Southeast Asia to Australia), there was a mass extinction of all of the most specialized metatherian endemics. In the northern continents of Eurasia and North America, and Africa, where there were large placental mammalian presences…there were essentially no pouch-bearers to be found…and when placentals invaded metatherian territory, the dethroning was swift and bloody. This occurred without fail, for millions of years, resulting in a comparatively very low species diversity of metatherians compared to their eutherian overlords.


So, why is it, exactly, that metatherians have wussed out in competition with eutherians, over and over and over again? It would be tempting to say that metatherians are somehow ‘less evolved’ and inherently ‘inferior’ to their eutherian counterparts. However, evolution doesn’t work like a linear ladder from ‘least evolved’ to ‘most evolved’. Marsupials and their kin are simply an old offshoot of the main mammalian line, and they have gone through just as much adaptation and retooling in response to their environment as eutherians, often with even more specialization (see: Thylacoleo from Part 1). Marsupials aren’t ‘less evolved’ than placentals; they just shared a common ancestor with placentals much further back than placentals do with each other. However, that doesn’t mean that there aren’t certain aspects of marsupial/metatherian biology that may have put them at a disadvantage against placental invaders.

But first, there are certain pros to being a metatherian. The most obvious is tied to their brand of reproduction. Marsupials completely side-step a lot of the risks associated with pregnancy and long gestation that are common to placental mammals. Marsupials produce very small, undeveloped young, sometimes only a couple weeks after zygote formation. This means that female marsupials spend a minimal amount of calories on pregnancy, and in times of stress or crisis, can lose or terminate the offspring without much ‘wasted effort.’ This also reduces the amount of danger to the mother if she is pregnant during times of scarcity; there’s not a giant ‘energy sink’ that puts her at risk of starvation or malnutrition. Marsupials are far more flexible when it comes to the initial process of reproduction, and large marsupials of the same mass as a placental counterpart typically will have much higher levels of lifetime reproduction in comparison. The tiny size of the offspring even at the peak of pregnancy, smaller than a jelly bean, means that there is no ponderous, debilitating pregnancy common to many placental mammals. This relative, temporary reduction of mobility is very dangerous to female placental animals, especially if they are prey items. This is probably most pronounced in human females, who are not only lucky enough to have very long gestation periods, but also are bipedal…which makes everything even harder.
Marsupials also avoid the risks associated with the birthing process, since the joeys are so tiny when born.

This would seem to be a huge advantage for marsupials. Female marsupials churn out minuscule joeys like ambulatory jelly bean factories, hardly missing a beat between pregnancies. Sure, a lot of these joeys die before maturity, but it’s no sweat for mom, who can just make half a dozen more next year. Placental mammals go through an arduous process growing a gigantic offspring, which acts like a brick of lead in the gut when fleeing from predators, and could actually kill the mother whenever it decides it’s time to move out.

Another advantage, it would seem, especially for carnivorous marsupials, is that across the board, pound for pound, marsupials possess significantly stronger bite forces than placental mammals. Thylacoleo could produce the strongest bite force, per kilogram, of any mammal ever. The thylacine (Tasmanian wolf) had a stronger bite than a comparatively sized gray wolf. Various living species of carnivorous marsupial have among the most powerful jaws in the whole mammalian class.

But of course, those pros are a mote of dust in a cavern of cons for marsupials. Most of these, interestingly enough, are caused by their reproductive strategy. Yes, marsupials have far more efficient pregnancies than placental mammals, but that is just one facet of reproduction.
That whole short pregnancy thing actually has its origins in a relatively underwhelming quirk of marsupial reproductive biology. In placental mammals, soon after fertilization and the growth of a blastocyst (a transitory mass of cells that will eventually form an embryo), a layer of cells encases the newly forming offspring. This is known as the ‘trophoblast’ and it serves to protect the progeny from…the mother. Since the offspring has genetic material from its father, a foreign entity, the mother’s immune system, relatively quickly in the pregnancy, would attack and reject the unknown lifeform. The trophoblast acts like an invisibility cloak, hiding the offspring from mom’s trigger-happy immune responses. It also is instrumental in the attachment of the blastocyst to the wall of the uterus and the formation of a placenta.
An awesome set-up, right?
Well, marsupials don’t have any of that going on. They do not produce nice little trophoblast cages around their rapidly-budding prides-and-joys. Instead, they simply engage in an insanely short pregnancy…before the mother’s immune system can tear apart Baby like a dutiful guard dog. Marsupials obviously take this situation in stride, but it leaves them with a number of obstacles that are not shared with their placental cousins.

For one, although their pregnancies are much shorter and use much less energy, marsupials have a very protracted nursing period on the other end. This means that marsupials have their kids on the teat, literally, far longer. Milk is really, really energetically expensive to make, compared to feeding an offspring in utero via a placenta. Instead of just dipping into the sugar/carbohydrate/protein/fat stores that mom has been taking up in her food supply, marsupials take food energy that the mother has processed, and then uses that to make a secondary milk product for the joeys. That extra step loses a lot of energy, and puts extended strain on the mother that placental mammals never experience. It’s like ordering delivery pizza, but sending it to a location 10 miles from your apartment, which means you need to get in your car and drive over to pick it up…when you could have just sent the damn thing to your front door.
As I’ve said before, nature (through evolution) is a merciless accountant. Energy waste does not escape tallying, and if the new crew in town is better with their expenditures than you are, it won’t be long until your species is reduced to a few dusty, plushy additions to museum collection, and nothing more.

Another effect of that short gestation is some serious impact on development after birth. Newborn joeys have to, crazy as it sounds, climb along the mother’s fur from the birth canal all the way up to the pouch, where it attaches itself to a nipple and doesn’t really budge until much later in development. Keep in mind that this is a fetus; blind, pink, without even facial features or hind limbs…and it has to drag itself through a thicket of fur for the equivalent of hundreds of feet, and get to the right destination. The mother also doesn’t really help out much. Some species may lay down a wet saliva trail for the joey, but that’s about it. Perhaps they figure if the little bastard is going to be living rent-free in a pocket made out the mother’s own flesh for months on end, then they can figure out their own damn way there.
This epic journey requires that even at such a rudimentary developmental stage, the joey must have overly-developed forelimbs, strong enough to pull the nubby body that great distance. These forelimbs must also be able to grasp and lock onto the fur. This severely limits the evolutionary avenues for marsupials in general; because of this reproductive strategy, climbing forelimbs must be in play. That is why there are no fully aquatic marsupials with flippers, no flying marsupials with wings, and no hoofed marsupials. With Australia’s wide, flat plains, you would expect a whole host of fleet, running, herbivorous marsupials to evolve, but because of that need for a climbing forelimb, you get things like kangaroos instead. There are gliding marsupials, but no flying species. You’ll never see a marsupial ‘whale’, a marsupial ‘bat’, or a marsupial ‘horse’. Marsupial reproduction is a massive wet blanket on evolutionary creativity in locomotion.

The early affixture of the joey to the nipple also limits cranial development. There needs to be early ossification (the setting of bone in place of other tissues like cartilage) in order to do anything like use force on the mouth to attach to anything. The head being a big blob of amorphous crap isn’t going to work. This early bone growth in the head of young joeys impacts head development further down the road. Marsupial brains don’t have the same amount of time for growth and expansion of size, which results in smaller brains in adults. Almost without fail, in comparisons between marsupial skulls and placental skulls from animals of equivalent mass and ecological niche, the brain case is a good deal smaller in the marsupial example. This is most noticeable in the neocortex, that area of the brain that allows for cognitive process and more abstract thinking and planning. This is partially the reason why there are no intelligent, marsupial ‘monkey’ equivalents. It may be that placentals in the same ecological niche as a given marsupial are simply more intellectually capable, and more adaptable on the fly; this would translate into some serious competition troubles for the marsupial.

Marsupials also have some differences in brain morphology and anatomy compared to placentals. Marsupials lack a corpus callosum, which is a structure in the brain that connects the tissue of the left and right hemispheres of the brain. Only placental mammals have this feature, and it is thought to be instrumental in the streamlining of information transfer and communication between two hemispheres of the brain. It may be that in ecological confrontations between invading placentals and marsupials, a major factor in competition is the fact that placentals had an extra intellectual edge, and were able to process information and adapt to their surroundings in a more effective way than endemic marsupial species.

Placental mammals also had an edge just in their evolutionary history. For tens of millions of years, placental mammals toiled in the cauldron of natural selection that made up the northern continents and Africa. These were massive land areas, with variable and unpredictable elements that needed to be overcome; plate tectonics, climate change, and range expansion into novel environments were commonplace, and lineages of organisms not able to cope with such rapid changes were quickly extirpated from the environment by natural selection. Whole orders of placental mammals rose and fell into extinction over this period of time, and due to the brutal nature of being in such a diverse and rapidly changing environment, cumbersome ‘experimental’ forms and strategies that couldn’t cut the mustard were cropped away. In contrast, on the small southern landmasses of South America and Australia, which were islands, there were no regular transferals of new organisms from outside sources into their environment, through climate change or the movement of the plates. The challenges that honed and culled and obliterated scores of lineages of placentals were not shared by marsupials to the south; they had a very stable 60 million years or so after the dinosaurs went extinct. Niche competition was something marsupials had not as often encountered, so this led to specialization and an inability to adapt to new factors in their ecosystem.

The greatest metatherian megafauna were outsmarted, they were rendered too reproductively inefficient, and they were far to inflexible. The remaining species, already facing threats from human encroachment, are fighting the same battles against all the placental invasives that humans bring along with them (cats, foxes, rats, pigs, etc.), and they are losing quite badly. Most of the animals in this entry are on some level endangered (some critically so), and some are as rare as other famously uncommon animals like pandas and tigers…but get no attention, mostly because they aren’t ‘charismatic’ enough to be marketable as an example of biodiversity in distress.

One group of marsupials containing some particularly rare members is the tree kangaroos. And no, I’m not making that up. There are kangaroos that live in trees and they look like this:

If you’re thinking to yourself ‘how the hell does a kangaroo get up in a tree?’ then know that you are correct in being skeptical. A kangaroo trying to climb a tree is like a human trying to do the same thing, but with skis attached to their feet. The thin, long feet of most kangaroos are ideal for launching the body off the ground, but don’t have much function beyond that. Tree kangaroos, all members of the genus Dendrolagus (which literally translates to ‘tree rabbit’), have gone through some modifications that have allowed them to recolonize the rainforest canopy.
I say ‘recolonize’ because the ancestors of kangaroos started off in the treetops, like many generalist, arboreal marsupials shortly after the dinosaurs went extinct. The earliest ancestors of kangaroos, as well as lots of other members of the Diprotodontia order, were likely tree-dwelling possum-like (not to be confused with opossum) herbivores. As the Australian continent dried, the rainforests retreated, and some of these possum-like animals became terrestrial, grassland animals that locomoted on their hopping hind legs. During this time, their broad, grasping feet became thin and sinewy for the hopping, ground-dwelling lifestyle; this trend culminated in the specialized elastic springs that move large kangaroos and wallabies along the deserts and plains of Australia today.
One group of rock-wallabies, back in the mid-Miocene some 15 million years ago, had returned to the forest environments in northern Australia. These forests were different than the ones that the first macropods (kangaroos) left for the Australian savannah, and were instead a type imported from the Indonesian islands and Southeast Asia. These versatile and agile rock-wallabies eventually started spending more time in the trees, and their hopping back feet started, over the generations, re-broadening into a more appropriate shape for life in the forest canopy.

The above illustration shows the hypothesized progression in foot morphology, using modern analogues, starting from a possum ancestor, continuing through forest floor kangaroos, to rock-wallabies, and back to the trees with Dendrolagus individuals.
Tree kangaroos currently occupy a range that includes Papua New Guinea, various other east Indonesian islands, and extreme northern Australia. They are restricted to rainforest habitat, and tend to inhabit higher elevation areas that receive even more precipitation. They are, of course, herbivorous, and many species subsist on a wide range of forest plant material. Tree kangaroos are awkward and clumsy on the ground, and tend to spend as much time up in the tree tops as possible. This complete dependence on their rainforest home means that they are more sensitive than most animals to rainforest logging and habitat loss. Their range extending primarily in one of the least populated forest areas in Australasia also means that they are rarely seen, and make themselves hidden to humans and other predators (which include pythons, marsupial carnivores, and birds of prey).

One species that is especially threatened is the Matschie’s tree kangaroo (Dendrolagus matschiei) of the Huon Peninsula in eastern New Guinea. They inhabit the mountain forest there on the rugged peninsula (and only on that peninsula) up to 10,000 feet in elevation. The joeys of this species also look a little like ewoks.

Welcome to Endor! May I take your coat?

Look at that cute little shit! It’s surprising to me that there isn’t more worldwide outrage, pledge drives, and ‘Save the Roo’ merchandise being hawked for this animal’s survival. It looks like what emerges from the very bottom of a pit of adorable Pokemon starters, Internet bunny videos, and every carnival plush animal on the planet after decades of fermentation. I’m still slightly suspicious that it was developed in a lab specifically to be a widely loved ‘spokesperson’ for fabric softener commercials. It’s an organism of unrealistically pure, distilled, baby-talk inducing infatuation. You drop a crate of tree kangaroo joeys into the middle of war zone, and you’ll have peace in ten minutes.
Basically, what I’m trying to say is that this thing makes panda cubs look like that pile of gunk in your yard that may or not be dog puke. The stuff with the white mold on top.

Such a nice moment almost makes you forget that they are going extinct. And they are.
Matschie’s tree kangaroos, like all tree kangaroos, are specialized canopy dwellers, and as their habitat is cleared for lumber production and for crop planting, they don’t have any options but to die. While they have, somehow, escaped the exotic pet trade, humans also more directly impact them by hunting. The people of Papua New Guinea have hunted them for millennia for meat and their soft fur. This was done at subsistence levels in the past, but the combination of habitat destruction and increased human population and hunting is taking its toll.
It doesn’t help that these kangaroos don’t have a lot of defenses. They can’t rear up and use their legs as weapons like their ground-living cousins. The Matschie’s tree kangaroo, for example, has only one real option for escaping predation, and it involves hiding. The high altitude cloud forests, thousands of feet up in the mountains of the Huon Peninsula, are a place that has quite a bit of moisture in the air. The ‘cloud forests’ are so called due to a nearly constant presence of overcast and dense fog, saturating the rainforest air. Because of this, there is a lot of moss that can survive and absorb water from the fog up in the canopy. Great, brownish mounds of moss cover portions of tree branches across the canopy. That reddish-brown coloring of the Matschie’s tree kangaroo helps them blend in with the moss when they feel threatened. Yes, this is an animal so benign and harmless that it takes refuge in moss…the plant world’s fluffy pillow. Only an animal that looks like the Matschie’s tree kangaroo would decide that the perfect thing to do in a crisis is to find a place comfortable enough to take a nap.

Jesus, zookeepers. You could have at least gotten him a Tempur-Pedic.

There are efforts by conservation groups and scientists to save this species, among others in the tree kangaroo genus, and there has been promising co-operation with various remote townships in New Guinea to start setting aside areas for these animals without interference. Some populations exist in zoos across the world, but hopefully these won’t be the species’ final homes. Luckily, tree kangaroos tend to thrive in captivity (unlike those libido-less pandas), so there is little danger that this species will go extinct in the proper sense, but obviously no one wants to see the wild population dwindle to nothing. If that day is inevitable, one can only hope that caretakers in the future remember not to feed them after midnight. For the love of god, don’t feed them after midnight.

Tree kangaroos aren’t alone as the only arboreal rainforest marsupials in their home. Inhabiting the same general region as the tree kangaroos, the rainforests of Indonesia and northern Australia, is this thing:

It may look like some ungodly combination of lemur, dairy cow, and gecko, but it’s just another weird-ass marsupial. This is a common spotted cuscus (Spilocuscus maculatus), one species in a group of possums (Phalangeridae) known as cuscuses…all of them sharing long, partially naked prehensile tails, smallish ears, and a slow, measured way of movement not unlike sloths or lorises. Their odd appearance and slight lemur-like appearance caused much confusion when cuscuses were first encountered by Western scientists. Cuscuses were assumed to be primates at first glance, and ecologically speaking, they really are the closest marsupials have gotten to evolving a prosimian primate equivalent to the placental versions. The name may look like ‘couscous’ (“the food so nice they named it twice”), but it is pronounced ‘cuss cuss’, which is an onomatopoeia of the hissing noise they make when threatened. There are actually four different genera of cuscus, Spilocuscus just being one example, and they vary in coloration and general appearance widely. Most of them are native to the same rainforest region, and they all tend to fill similar ecological niches as their more nimble possum brethren, munching on leaves and fruit up in the treetops. They are all very nocturnal, and possess large eyes and a facial expression that perpetually makes them look like they just discovered they left the oven on.

The common spotted cuscus is somewhat unique among cuscuses in that its diet is a little more generalized and it has been seen feeding in the daylight hours, which is something unheard of in other cuscuses. They can grow to about the size of a house cat, and live exceedingly solitary lives, only interacting favorably in times of mating. Males of this species are highly territorial, and mark their claim in the canopy by using a potent musk and their own saliva, which they coat tree branches with. Transgressions by other males are met with surprising levels of aggression, noise, and violence.
Spotted cuscuses have a diet that is mostly comprised of leaves, fruit, and flowers, but will also consume insects and bird eggs, and anything else slow enough to get caught in its path.
Males in this species are almost always spotted with gray or brown blotches, while females are more often purely white or purely gray in color. Male coloration is odd, but female coloration, in the darkness of the rainforest, must be striking.

Who taught that seal pup how to climb trees?

That’s the other thing too; like tree kangaroos, cuscuses, with their soft pelts, fat, slow bodies, and giant eyes would theoretically make for brilliant poster-animals for conservation efforts. However, cuscuses, with the exception of the bear cuscuses in the genus Ailurops, there aren’t any immediate threats to their survival. Cuscuses are used for food and fur in New Guinea, and there hasn’t yet been a major blow dealt to their species integrity.
Cuscuses in general are an integral part of traditional life in many parts of Papua New Guinea. Their meat is an excellent source of protein in the rainforest, and their fur is used to make ceremonial headpieces and other ornamentation, often highly cherished and passed down from generation to generation. Since cuscuses are incredibly shy creatures, and very rarely seen in the forest (even by the New Guineans who live in close proximity to the wilds their entire lives), actively hunting them isn’t feasible. Instead, many are hand-reared as pets, and then eventually killed in adulthood. The cuscus, if reared from infancy, can actually be an easy to care for pet. They don’t tend to stray too far or move too quickly, they lack any real capacity to do a lot of damage if they do happen to become aggressive, and their instinct to clasp onto high objects means that they spend a lot of their time crawling all over and perching on their owners. They are reportedly fond of clinging stubbornly to human heads and hair, so they can get a good vantage point on their surroundings.
I’m not sure what the legality of keeping cuscuses as pets is outside of New Guinea, but I would bet on the side of illegality, and of course, immorality. Removing wild animals from their home ranges for introduction into a pet trade is never a good decision. I’m not sure how successful a cuscus pet trade would be, even if they are reportedly mellow pets and have all the fuzzy appeal, they might not catch on…mostly because they have startlingly creepy eyes. Really, really creepy.

“Sauron demands more starfruit!”

Enough, you say! Enough with the cute, fluffy herbivores. Certainly there are some overlooked, underloved, and unappreciated carnivorous metatherians to explore, yes? The answer to this question is yes. Although great, giant carnivores like the marsupial ‘lion’ and the sparassadont ‘sabertooth’ from South America are gone, as are the thylacines, some carnivores do remain. In some ways, they are even more acutely threatened from changes to their environment. Not only are they often shoved out of their niches by invading placental carnivores like foxes and cats, but can fall prey to even larger predators like dogs and dingos, and have issues with invasive food items that initially seem like a good idea to try and eat (see: cane toads).
The remaining metatherian carnivores are all in the order Dasyuromorphia. Most are quite small, being mouse-sized predators of things like insects and small lizards. Some are larger, filling the niches of foxes and cats and weasels (precisely why they are so sensitive to those same animals running amok in their habitat). Up until the 1930s, the largest members, the ‘Tasmanian wolves’ filled the large dog niche…and then they went extinct. Another crowning achievement for humankind, I’ll tell you what.
There are only two families remaining in this order, and one of them, the Dasyuridae, is the third largest family of metatherians. This family houses the vast majority of the Dasyuromorphia, and is made up of short-legged, long-snouted carnivorous animals ranging from the size of a shrew to the size of a small dog in the case of the Tasmanian devil (Sarcophilus).
While the Tasmanian devil is somewhat more familiar to the majority of folks outside of Australia, its smaller, more wide-ranging cousin, the quoll (a member of the dasyurid family) is not.

There are six living species of quoll (genus Dasyurus), and they range across parts of Australia (mostly near the coasts), Tasmania, and Papua New Guinea. Most are threatened with extinction at some level, some more severe than others. They are essentially marsupial ‘ferrets’, and are nimble, agile predators of both terrestrial and arboreal environments. Due to their superficial appearance to cats or any other small placental carnivore, they were originally referred to as ‘native cats’ by the first Europeans in Australia. The name ‘quoll’, like so many other names of animals in Australia, is a corruption of the Aboriginal name for the same creature. In the Guugu Yimidhirr language (from northeastern Queensland), these little guys are called ‘dhigul’. ‘Quoll’ is about as close as clumsy European tongues could get, apparently. Comparisons with placental ecological equivalents led to other inaccurate naming schemes like ‘spotted marten’ or ‘spotted opossum’ (again, this is an animal very different from American opossums).

There are multiple prehistoric species in the fossil record from around Australia, New Guinea, and Tasmania, and genetic clock studies infer that quolls diversified in the Miocene epoch between 15 and 5 million years ago, coinciding in a larger, rapid diversification trend in Australian marsupials. Most of the direct ancestors of today’s six species had diverged more than 4 million years ago. Up until very recently, they were found all over Australia, Tasmania, and New Guinea, but now exist in distinct, fragmented geographic areas.

As far as marsupials go, quolls are fairly conventional, despite having the distinction of being the most massive group of carnivorous marsupials still living on the Australian mainland. Mating occurs in the winter, and three weeks later, the female gives birth to as many as two dozen pups, each only the size of a grain of rice. However, since there are only a limited number of teats for them to attach to, most of these young will die. The mad dash to the pouch for these numerous, primordial offspring becomes a contest with life or death consequences. Right out of the vaginal gate, quolls are expected to best their own brothers and sisters in a race to end all races. With this kind of Spartan upbringing, it’s hard to imagine quolls as being anything more than sociopathic.

That, my friends, is the face of an animal that just got done pooping in your hand. Why? Because fuck you, that’s why.

After the lucky six or so that manage to reach the teats first grow to a much higher level of development, all the while surrounded by the decaying corpses of their diminutive, forgotten kin, they venture out of the pouch and attach themselves to the back of mother, where they remain, piggy-backing, for several more weeks. This is a behavior that many in the States have likely seen with opossums.
Quolls, like many marsupials, do not live very long in comparison to placental mammals of the same mass. Quolls reach maturity at a year old, and typically have a lifespan of two to five years. They may be of the same size as a house cat, but they live a fraction as long.

Their cute exterior, made up of delicate white spotted patterns and pink wet noses, masks their status as apex predators.



Those dagger teeth and four sets of curved claws aren’t just for show. Quolls eat just about everything that moves, snapping up large insects, frogs, lizards, birds, and smaller marsupials. Larger quolls, like the tiger quoll (Dasyurus maculatus), may prey upon possums, invasive rabbits, and even outwardly unappetizing animals like the echidna, flipping it over on its spiny back and gouging out the belly. Prey is dispatched with a swift pounce, followed by jaws clamping down on the neck.
It is actually this habit of trying to eat anything once that is one of the factors damaging the quoll’s chances for survival. Cane toads (Bufo marinus), which are massive toads native to Central and South America, were brought to northern Australia to held eradicate insect pests in sugar cane crops. Of course, the population has since exploded and now cane toads are ravaging the ecosystems of provinces in northern Australia. They’re big enough to eat small native animals, and when larger native animals try to feed on them, they puff up and lodge themselves in the throat on the way down, suffocating the unfortunate diner. They are also highly toxic, which means even if an animal is too small to try and swallow it whole, it will still die from the poison. Cane toads eat everything they find, can’t be eaten by anything themselves, and they multiply like crazy…because, of course, even their tadpoles are toxic. They’ve grown to such plague-like numbers that you can drive through parts of rural Queensland where the road is plastered with the bodies of thousands of road killed cane toad carcasses. Due to their harmful presence, people are actually encouraged to try and hit them with their tires on highways, popping them like brown, noxious, meat balloons. Because Australians don’t fuck around.

Highway of Broken Screams

Quolls not only have a hard time dealing with cane toad toxins, and the fact that cane toads will actually devour a lot of the prey animals that normally feed quoll juveniles, but their carnivorous habits are also hurting them in another way. The poison sodium monofluoroacetate is put out into the wild by well-intentioned humans attempting to control populations of invasives like rabbits and foxes and wild dogs. It is sometimes put into cooked meat in order to attract problem carnivores, but is instead eaten by quolls. The poison isn’t quite as toxic to quolls as it is to target canids like foxes and dogs, but smaller animals can easily succumb to the effects. Ironically, efforts to rid the environment of damaging feral competitors of the quoll may actually do more damage.

Quolls are definitely in danger of dying out, since they are dealing with challenges from every possible angle. One somewhat odd idea that has been gaining more attention lately is the possibility of convincing Australians to start hand-rearing quolls as pets instead of comparable, ecosystem-wreckers like cats or ferrets. Quolls are relatively easy to care for, about as friendly as a cat (not saying much, I know), and an effort like this would create a ‘bank’ of individuals in domestic situations in case wild populations crash. Some folks are already breeding them, but it is unknown if the idea will catch on. For one, their short lifespan may be an issue. People are generally ok with the realization that their goldfish may not last more than a month or two. The idea that their fuzzy, big-eyed, mammalian companion that they hand-reared from a tiny pup will likely drop dead before its 4th birthday is more foreign.
Also, there’s the consideration that they are still wild animals, despite being ‘tamed’, and have to capacity to become aggressive (especially if other quolls are around, being the territorial hunters that they are).

“AAAUGH! Get it off! The cute….it BURNS!”

The next metatherian on this list is technically a member of that carnivorous Dasyuromorphia order, and is relatively closely related to quolls, Tasmanian devils, and the like, but it is definitely a weird example. It is known as the numbat (also called the ‘walpurti’ and the ‘banded anteater’), and while it used to be widespread across southern Australia, it is now restricted to several tiny areas along the southern and western perimeters of the continent and is severely endangered. It is the only species in the genus Myrmecobius and the only member of the family Myrmecobiidae, meaning it was unlike anything we know living.

What are you?!

Genetic studies place it in with the Dasyuromorphia, but it likely diverged from other members as far back as 40 million years ago or so. It appears to be a highly-derived offshoot dasyuromorph that has taken up a lifestyle of eating small insects (termites, to be exact), and only that. The numbat could be erroneously called a marsupial ‘anteater’ (since it only eats termites), and is a striking example of convergent evolution on a common form evolved several times across the world; anteaters in Central and South America, aardvarks in Africa, pangolins in Africa and southern Asia, armadillos in the Americas, the echidna of Australasia, and finally the numbat. In order to engage in this diet, it has specific adaptations, including reduced, non-functional teeth, and a ridiculously long, sticky tongue.

How do you even have room in your head for that thing?

Numbats are unusual among marsupials, especially small, squirrel-sized ones, in that it is diurnal, meaning that it is active during the middle of the day. It scampers around dry eucalyptus woodland undergrowth, digging with its strong front claws to uncover termites beneath the soil at the base of mounds, where it then laps them up.
Numbat females are also unique in that they don’t have an actual pouch. Going against the grain and potentially losing their marsupial card forever, numbats have secondarily lost the pouch, and instead have a simple patch of stiff, matted hair that covers and protects the four teats.

Numbats suffered their dramatic drop in numbers solely at the hands of European foxes, which were released in Australia in the 19th century. Numbats don’t have a lot of defenses, and are the perfect size for a fox to pick up as a snack. It also doesn’t help that numbats are active during the day and can’t avoid predators in a way more common to animals their size. Also, their natural predators, predators that they had evolved to cope with, were all birds of prey or large snakes; numbats are relatively unfamiliar with this diurnal, terrestrial, mammalian predator shit (quolls would hypothetically be an issue, but quolls hunt in the nighttime). It’s like studying for weeks to take the SAT, only to find out that the main criterion you’ll be judged on is how well you can whistle. It’s not exactly a fair situation.

If tiny, termite-eating, tiger-striped squirrel things like the numbat weren’t weird enough, then get a load of the bilby (Macrotis lagotis) of the arid interior of Australia.

You’ve got to be fucking kidding me.

This is, apparently, what happens when a rabbit gets its face stuck in a Chinese finger trap  for a few years. ‘Bilby’ is a short name for what is, from initial appearances, a ponderous chimera of a bunny, a shrew, and a pig, mashed together in a comically ridiculous mockery of the natural order.
This marsupial is only surviving member of its family (Thylacomyidae), and is a member of  the Peramelemorphia order, which is comprised of bilbies and their more populous, less weird-looking cousins, the bandicoots. Yes, Crash of “Crash Bandicoot” fame was based on a real animal. These critters are essentially the ‘marsupial omnivores’ group, ranging in size from about that of a mouse, up to the size of a rabbit (larger bandicoots and the bilby). Many species appear to be plump, elongated, giant shrew-like animals, but they have diets that more closely resemble those of pigs. Peramelamorphs, including the bilby, will root up insects, small animals, fruit, roots, seeds, fungi, and whatever else they find along the ground.

Bilbies are nocturnal, and use their Dumbo-esque ears to listen for predators in the night, as well as grubs and insects along the earth. They are superb diggers, unlike their bandicoot relatives, and dig networks of tunnels in the hot, dusty, desert earth to rest in during the day.

The bilby is currently threatened with extinction due to factors associated with invasive species, most notably foxes, cats, and rabbits. Foxes and cats are adept at killing and eating bilbies, and rabbits, burrowing animals themselves, disrupt and collapse bilby burrows with their own habits. Rabbits also eat a lot of the same foods as bilbies, and have been rapidly starving them out of areas where rabbit populations are high.
Livestock, like sheep and cattle, also consume bilby resources and crush bilby burrow systems. If that wasn’t enough to make you feel the pangs of guilt, consider that in addition to all of this, humans also hunted bilbies for their meat and fur (albeit in less impactful ways than the fallout from invasives). Think of all of that next time another image of a woefully endangered bilby pops up. Like right now.

“That cow crushed our burrow. How will we survive in this harsh desert?”

There are plenty of efforts mounting to save this animal (which may number less than 1000 individuals in the wild), ranging from largely successful breeding programs, to re-branding the Easter Bunny in Australia as instead the Easter Bilby to raise awareness. This, of course, makes perfect sense; the pouch would be a very convenient place to carry a load of eggs. Maybe the Easter Bunny should start watching his back…

Surely, you think, it can’t get any more odd than the bilby, what with its skinny legs, giant ears, and tube-shaped nose…it looks like something that would scuffle around the sands of Tatooine before being squashed by a bantha or something (don’t lie, you totally understood that reference). Surely, the bilby, with its alien charm, is the zenith of marsupial strangeness in the barren sands of interior Australia.


Imagine you’re a lizard, scampering swiftly across the blistering hot sands of central Australia. Even for you, the heat is too much, so you stop and shuffle yourself underneath the sand some to cool off. Your little reptilian heart is fluttering in your scaly chest and you begin to relax. But then, you sense something quickly flying through the sand behind and below you. Before you can react, it’s all over.


Rising from the sands, intercepting its prey like a great white shark torpedoing itself at a sea lion, is the terror of the deep desert; the marsupial mole (Notoryctes). The only marsupial known to have evolved to a chiefly subterranean existence, it is a fucking alien thing to look at. First off, it is completely blind. Its eyes have become vestigial, and exist only as remnant lenses just below the skin. It’s small and stubby, its body shape reminiscent of a hamster, perhaps one born with every chromosomal error possible. Beneath its silky, cream-colored coat is a body rippling with hardened muscle; toned and sculpted by a life of pushing itself through sand dunes.
In order to do this, it has two massive front limbs (attached to strong shoulders), each ending in a two-clawed shovel, which doubles as a pair of pincers when tackling larger prey…which it mashes up with a mouth full of sharp, diamond-shaped chompers.
Its path through the sand is aided by a hard, leathery shield of skin at the front of its conical face, and its hind limbs have been flattened into a paddle shape to push the sand behind itself as it moves forward. Its neck vertebrae have fused together to help turn the front of its body into a rigid sand ram; this particular adaptation has never been seen in any other burrowing mammal.

When it isn’t devouring every small desert creature in sight (or, uhm, non-sight), it takes the time to procreate. Females have a pouch that opens backwards, as to avoid it filling with sand as the animal digs. It only has two teats, and can carry only two offspring at a time…because who has time to babysit when you’re busy forcing your body through the fucking earth?

Although it’s called the marsupial ‘mole’, this animal has less in common, ecologically, with true, placental moles than it does with another group of ‘moles’, known as golden moles (family Chrysochloridae). The true moles most of us are familiar with (the ones that turn moist lawns into impromptu mine fields) are members of a clade that includes animals like shrews and hedgehogs. Golden moles, native to sub-Saharan Africa, are more closely related to things like elephants, sea cows, and aardvarks than ‘true moles.’ Golden moles are blind like marsupial ‘moles’, and have a lot of similar traits, including the ability to burrow in arid areas and the possession of large spade-shaped claws and a nose shield. This similarity between golden moles and Notoryctes is a clear example of convergent evolution in action.

Notoryctes contains two species that we know of, the northern and southern varieties, and they occupy large regions of the most isolated and arid parts of central Australia. We’ve known about their existence for more than a century, but they are probably the most poorly understood group of marsupials alive today. Most of this is because they live in a highly inaccessible region of the world, and even active searches for them often come up dry (pun intended). They are either incredibly rare, or just elusive. Since they burrow in sand, and their path fills in behind them, they have no permanent ‘base’ that we can find them in like other burrowing animals. They just swim through the sand as nomads, like miniature Ozzie graboids, chasing and unleashing hell upon anything on the desert floor.

“That’s how they get ya. They’re under the goddamned ground!”

Marsupial moles only turn up sparingly, maybe five to ten times per decade. Because of this, we almost know nothing about them. Their reproductive habits are a mystery, and so is a lot of their other behavior. We have a general idea of what they eat, but that’s about it.
We’re especially confused on how they’re related to other marsupials, and what their evolutionary history was like. Scientists have placed them in their own, separate order (Notoryctemorphia), and our limited molecular data seems to support this distinct status. From what we can tell, they diverged from other marsupials WAY back; between 50 and 64 million years ago. Morphological features haven’t helped much, and only hint, maybe that they might be distantly related to bandicoots and bilbies. Even with the luck of discovering a fossil specimen of an ancestor from more than 15 million years ago (Yalkaparidon), we still don’t know what the hell this animal is, phylogenetically. The fossil had features of both bandicoots (the skull base shape) and diprotodonts (the front incisors were similar).
However, the fossil, since it was from an area that was at that period of time tropical rainforest, tells us that it is likely the marsupial moles evolved in a wetter, forested environment, possibly burrowing through loose soil and leaf litter. When the climate changed and the continent became more arid, they would have already been well-adapted to the subterranean lifestyle. It would have been a change of scenery for them, but the job would have been the same, more or less.

As of right now, due to how rarely encountered both species are, they are both listed as endangered. Remains have been found in fox scat at a disturbingly high rate, but it is hard to tell exactly what the conservation status of these animals actually is. This reserved approach to their status remains likely until more data comes in about these bizarre critters.
Until then, all one can hope for is that they’ll continue their lonely, gritty lives criss-crossing the sand dune deserts without much interference.

“The Spice must flow.”

The last marsupial in this entry is not closely related to anything previously mentioned. It is a denizen of the Americas, from Mexico south through Central and South America down into Argentina. It is known as the ‘yapok’ or ‘water opossum’, and it is generally referred to as the most aquatic marsupial.

It also wins the title of ‘marsupial with the deadest eyes.’

Modern marsupials primarily diverge into two main groups; one that is found in Australasia and comprises most of what we know as ‘marsupials’ (and includes the highest diversity of form and families) and one that is found in the Americas, but mostly in Central and South America. The Australian clade, the Australidelphia, contains about 75% of all living marsupial species; kangaroos, wombats, koalas, possums, bandicoots, etc. The American clade, the Ameridelphia, contains the rest, and are generally referred to as the ‘opossums’, and they are found all over Central and South America, with one species (the Virginia opossum) managing to live as far north as Canada.
The only exception to this rule is a single, primitive species resting in its own special order (Microbiotheria), that is a member of the Australidelphia group, but happens to be native to the Chilean temperate rainforests.
The yapok is an ‘opossum’ and is separated from the ‘possums’ of Australia by many tens of millions of years. Saying the Virginia opossum we have in the U.S. is closely related to the brushtail possums of Australia is akin to saying armadillos are closely related to baboons.

Yapoks are unique in that they have a great deal of adaptations to a semi-aquatic lifestyle that are not found in other marsupials. Firstly, their black and white fur coat is dense and water repellent, as is typical in placental aquatic animals. The yapok solves part of the marsupial evolutionary puzzle regarding aquatic living by having the hind limbs deeply webbed for swimming, while the front feet are free of webbing and quite capable of grasping fish, frogs, and crustaceans…as well as fur in the joey stage on its way from the birth canal to the pouch.

“Hey! I believe I was promised fish.”

The yapok swims using its webbed hind feet and flat, paddle-like tail. In order to keep its joeys from being sent directly to a watery grave every time the yapok mother dives, the pouch has a key adaptation to aquatic life. It opens towards the back (like a marsupial mole’s does), and has a ring of strong muscles around the rim. Using these muscles, it can clamp shut with the young inside, creating a watertight seal.
Bizarrely enough, males in this species also have a pouch, although it isn’t used for helping out by carrying the joeys. No, rather than automatically take the ‘marsupial father of the year’ award, male yapoks use their pouch to protect their genitalia while swimming. Yes, yapoks are apparently so well hung that they have to tuck their junk in a skin pocket just so it doesn’t get caught on vegetation.
This was a feature that was seen in the (now extinct) thylacine males, for the similar reason of retracting their scrotum. In no other marsupials other than the thylacine and the yapok has this evolutionary obsession with potential penis endangerment been discovered.

Yapoks are about as close as marsupials are likely to get to evolving an ‘otter’, and as of right now, luckily, yapoks aren’t immediately threatened with extinction. They range over vast river basins all over the equatorial Americas, and as long there are plenty of aquatic prey items, and no invasive species to combat, they should be fine for a while, despite their luxurious, two-tone fur occasionally being used to make fur coats.

So, that concludes the extended, two-part series on metatherian oddities of the past and the present. From murderous, hook-clawed, mega-koala things in prehistoric Australia, to truck-sized wombats, to snake-eyed marsupial ‘sloths’, to nimble aquatic predators with an o-ring on their pouch…all treasures that tend to be concealed by our eutherian-biased outlook on the animal kingdom. Life on this planet is fantastically diverse, but as time progresses, that elegant complexity is falling away as innumerable groups of organisms, not only marsupials, succumb to the effects of human activity. I can only hope that at some point, after losing possibly too many gems in the crown of evolution, too many novel experiments, we finally realize that we can no longer destroy in centuries, what nature crafted over countless millions of years.

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Metatherians (Part 1 of 2): Extinct Megafauna


The immediate association most people have with the term ‘marsupial’ is that of fantastical, adorable, fluffy beasts in the far-away magical land of Oz, equipped with built-in fanny packs for storing their tiny, even more adorable, offspring. Bounding, big-eared kangaroos, sleepy koalas, and perhaps a hyperactive sugar glider or a waddling opossum might cross their minds. Not too far beyond this is where the train of thought pulls into its final stop, and suddenly they’re caught up in the romanticism of Australia itself; the sun-baked, tawny Outback scabland, didgeridoo droning in their mind’s ear, impossibly colorful fish flitting about the Great Barrier Reef, and perhaps Hugh Jackman or Nicole Kidman (whatever their fancy) driving cattle across the Northern Territory during The Dry.

While this idealization is all well and good, there is actually a lot more to these pouched animals than what fits on the in-fold of a Qantas brochure.
Marsupials are really bizarre by mammalian standards, and have a rich and relatively unrecognized evolutionary history that spans back 125 million years. This entry is one of two that will be devoted to these weird little creatures, focusing first on their unrealized illustrious past, and then on lesser known representatives of their clan in the present.

First, it may be helpful to actually define what, the grand scheme of things, zoologically, we are talking about.
Extant (or currently existing) mammals roughly break down into three groupings, which many folks learned back in their middle or high school science classes. Of these three, the one that split off earliest in the mammalian family tree are the Monotremes; egg-laying mammals. These anachronistic sideshows, the platypus and but a few species of echidna or ‘spiny anteater’ make up the entirety of what remains of this subclass. The other two, which last shared a common ancestor more than 150 million years back, are the Metatherians and the Euherians. Eutheria, meaning ‘true beasts’, contains the placental mammals (meaning that in fetal development, a placenta is present allowing nutrient and waste transport between the mother and offspring) that we are very familiar with. This is the group that contains everything else with fur and warm-blood that doesn’t lay eggs or have a pouch. Dogs, elephants, rabbits, bats, us…we are all placental, eutherian mammals.

The last group, the metatherians, meaning ‘behind beasts’ or ‘near beasts’, contain the marsupials (although, there used to be several sister groups under the metatherian umbrella, but they are now extinct).
The most glaring feature that distinguishes metatherians are their reproductive characteristics. The most obvious of which is the early birth of underdeveloped, jelly-bean sized young that remain in a pouch, or ‘marsupium’, firmly attached to their mother’s teat until they reach a more independent stage of development. This premature young, called a ‘joey’ is typically born after no more than five weeks inside the mother’s uterus. The marsupium itself is little more than a fold of skin specialized to cover the nipples of the mother and to safely house the joey as it continues its development.
Marsupials, and likely all metatherians, have urological and reproductive systems that would strike our Puritan eutherian hearts as alien. For example, female marsupials have two uteri, each one with its one vaginal canal, but the whole thing terminates in a single opening. A third vaginal canal, which can be permanent or temporary, in the middle of these first two, is solely used for birthing the joey. Corresponding to the two lateral vaginas, male marsupials have a forked penis. It should also be noted that marsupials have a single orifice for waste excretion, called a ‘cloaca’, that is also found in reptiles and birds. So, the penis in male marsupials is purely a sexual organ, and the careful re-routing of the urethra through it only arose in placentals like ourselves.

There are some other minor skeletal differences. For instance, marsupials tend to have more teeth than placentals; specifically in the number of pairs of molars. There are also some physiological differences, as marsupials tend to have a lower body temperature than placentals, as well as a shorter lifespan and comparatively slower metabolism.

Metatherians are thought to have split off from the mammalian line in the early Cretaceous, in Asia. Around 100 million years ago, the former supercontinent of Pangaea had rended itself into two main pieces, Laurasia in the north (containing North America and Eurasia) and Gondwana in the south (South America, Africa, Australia, India, and Antarctica), and Gondwana was being pulled further south and was splitting up into east and west factions. It is thought that early marsupials spread from Asia into Gondwana when it was still relatively close by, either directly, or through North America into South America (which were connected as late as 65 million years ago).
When the asteroid hit, and all the dinosaurs were powderized, mammals were suddenly free to exploit a large number of previously occupied ecological niches. Placental animals did very well across Laurasia, and in certain places in the old fragments of Gondwana, specifically Australia and South America, marsupials went through their evolutionary diversification.

The thing is, whenever placental mammals were introduced into ‘marsupial territory’ over these next 65 million years, usually by the aid of tectonic rearranging of plates, they would sweep in and outcompete their marsupialian brethren. There are plenty of theories as to why marsupials lost over and over again in these competitions, and I will go over them in part 2 of this series.
Marsupials never really got a good foothold in Eurasia, Africa, or North America; places where major groups of placental mammals, like dogs, antelope, big cats, rodents, primates, elephants, etc., really got off the ground and exploded in diversity. Metatherians in general did, however, make a respectable presence in South America in splendid isolation along with some equally weird placentals, and of course, most spectacularly, in Australia, which was almost completely devoid of a placental presence (outside of bats) up until around 50,000 years ago…when we charming lot crossed the Indonesian Land Bridge with half-domesticated dogs, fire, and weaponry.

Only 334 species of metatherian remain, compared to the more than 5,000 placental mammal species, and essentially all of these are centered around Australia, New Guinea, and South America (with one exception living in North America, a relatively recent transplant from the south, the Virginia opossum). The largest of them are kangaroos, roughly the size of a human being, and most living are small herbivores, insectivores, and some omnivores, with most carnivore lineages made extinct either by direct human extermination, or by introduced placental competition.
Of those that do remain, many are threatened by habitat loss from human encroachment and climate change, communicable disease (chlamydia in koalas, facial tumor disease in Tasmanian devils), and simply being slaughtered by non-endemic species that humans have brought in.
However, metatherians have a grand, and undeniably odd, evolutionary past that has littered the fossil record with scores of highly-specialized, fantastic species that are now long-gone, but nonetheless illustrates the great power of geographic isolation to facilitate evolutionary experimentation.

Let’s take a little tour, shall we?

The crouching (and possibly a little too thin) fellow above is Procoptodon goliah, alternatively known as ‘the giant short-faced kangaroo’ or more hilariously, ‘the whopper hopper.’ P. goliah was the largest macropod (kangaroo) ever to bound across the hot plains of Australia, and belonged to a now extinct subfamily of kangaroos, the Sthenurinae, of which it was the most extremely out-sized and specialized member. P. goliah’s genus dates back to throughout the Pleistocene epoch (up to around one million years ago), and suddenly went extinct around 50,000 years ago.
P. goliah, like all the sthenurines, was very large and robust compared to modern kangaroos, and was a browsing animal rather than a grazer like today’s kangaroos. It had an unusually short, flat face, and forward-facing eyes, possibly giving it an oddly primate-esque appearance. Unlike today’s kangaroos, it had only a single, hoof-like digit on its springlike hind legs. Assisting its diet on high-growing leaves and twigs were two elongated claws on each hand, attached to very long, flexible arms that it likely used to pull down branches towards its unsettlingly monkey-like face. These limbs stand in contrast to conventional kangaroo arms, which are comparatively short, stiff, and good for little else but scratching oneself and boxing. It probably helped, as well, that P. goliah, probably used its thick, powerful tail as a third leg for support when it raised up on its narrow feet to drag down vegetation, like some sort of alien, athletic ground sloth.

Procoptodon also had a killer hook shot.

Long, rangy limbs and big ol’ meaty claws were definitely an asset to the browsing lifestyle, but the fact that Procoptodon goliah was a gigantic fucker was likely more important. A modern red kangaroo, the largest living marsupial, can have exquisitely large males that reach heights of six feet, but are more typically in the four or five foot range. A particularly heavy red kangaroo can be 200 pounds. The whopper hopper, by comparison, would have had to duck slightly to fit through the front door to your house, and with its extended reach, could easily jam a basketball through the hoop without so much as a hop. Females of the species were large enough to stuff a 10-year old human child in their fathomless pouches and carry them off. In life, it was far meatier than the poor excuses for kangaroos we have today, and tipped the scales at more than 500 pounds.

In short, if modern kangaroos are deer, then this thing was a damn moose.

Fossils have been found all over mainland Australia, so it is likely that the giant short-faced kangaroo was relatively commonplace. With all that heft, it would have been undoubtedly been a coveted meal for any predator, and that may include humans.
Procoptodon, like so many other large marsupials in Australia, went extinct at roughly the same time as humans showed up. This seems to suggest that humans were the main cause, but such things are never easy to determine. For one thing, no bones have ever been found at butchering sites, or with markings that indicate human hunting and processing for consumption. So, it’s not even known definitively if humans actually hunted them at all. But, they would have been easy targets, that’s for sure. Big, easy to spot, and more bulky and slow then their modern cousins, they would have been a relatively easy thing to hit with a spear. In the event of somehow cornering one in close quarters, however, they would be exceedingly dangerous. One well-placed kick would turn a human abdomen into a scarlet waterfall of viscera.

Whatever the reason, Procoptodon vanished from Australia very suddenly, denying us the experience of seeing this massive animal in life. Australia still has plenty of kangaroos, but as is often the case with comparing modern counterparts to extinct prehistoric relatives (see: T-rex vs. sparrows) none of them are quite as imposing, unique, badass, or ‘sexy’ as the pug-nosed, late-whopper hopper.

“Draw me like one of your French girls.”

Another type of kangaroo that shared the arid landscape with Procoptodon was Propleopus. However, this kangaroo came from very different stock, being of the same lineage that the modern animals known as ‘rat-kangaroos’ of the Potoroidae belong. It was much larger than its diminutive, bunny-like modern descendants, growing up to around 150 pounds, making it about the same size as a typical red kangaroo. It lived around the same time as the whopper hopper, but its fossils have been very rare. So, you’re probably saying to yourself right around now, ‘ok, big rat-kangaroo (whatever the hell THAT is)…what’s the big deal?’
Well, here’s the kicker (so to speak); Propleopus ate meat.
Evidence for this comes from the most logical place to find out information about what an animal ate; the teeth. Propleopus had some eerie modifications to the typical plant-munching chompers of most kangaroos, including the addition of serrated edges on the normally universally blunt cheek teeth, as well as blade-like lower incisors that jutted out from the jaw like a bayonet.

All the better to spear you with.

While the concept of a carnivorous kangaroo leaping after prey and maliciously tearing it to shreds is surreally hysterical, and a bit unnerving, all this dentition means is that it was very capable of eating meat; it doesn’t mean it actually hunted prey. Propleopus also retained the capacity to process plant matter like fruit and soft leaves, so it may have been something more of an omnivore or an opportunistic scavenger of kills or reptilian or bird eggs. Either way, judging by the shiv sticking out of its mouth, and its general size, Propleopus must have been a soundly nasty creature if crossed. It’s possible that Propleopus was something like the baboon of Africa’s savannahs, a temperamental omnivore wandering the open country, searching for whatever it could mash up for food, even if it had to make it bleed first.

Propleopus is survived by ‘rat-kangaroos’ and ‘bettongs’, small macropods which rarely exceed fifteen pounds in weight and reside in Australia’s eastern coastal forests. These animals are, ecologically, something like the ‘rabbits’ of Australia, dining on herbivore fare, but will regularly indulge in darker tastes and harken back to their bigger, scarier ancestor by taking an insect or two, or perhaps scavenging on a sheep carcass.

Don’t turn your backs on these things. Pure evil.

While kangaroos were certainly more interesting and diverse several tens of thousands of years ago in Australia, there are more varieties of marsupial than the hopping kind. Many people are familiar with wombats; furry, short, squat, burrowing marsupials that somewhat resemble a cross between a teddy bear and a marmot, but can be about the size of a large badger. Wombats, members of the family Vombatidae, are fairly closely related to kangaroos, as they share the massive marsupial order of Diprotodontia. Wombats, however, are even closer in relation to koalas, and this can be seen in their similarly stubby, cuddly morphology…and yes those are scientific terms. Wombats, although meek and rodent-like today, had close relatives, even closer than koalas, that were the largest marsupials known to science. These giants lived alongside Procoptodon and Propleopus in this Pleistocene era of an Australian marsupial maximum of diversity.

Meet Diprotodon, the largest marsupial that ever laid a foot of its pouched self on this planet. Diprotodon existed across Australia from about 1.6 million years ago, until, unsurprisingly again, around the time humans arrived, about 50,000 years ago.
It was immense by marsupial standards. It grew to be six and half feet at the shoulder, ten feet in length, and as much as three tons in weight. This is comparable to the size of a hippopotamus, one of the largest land animals alive today.
We know that it inhabited areas close to water, unlike the desert-loving Procoptodon, and dined on the varied plants of the open woodlands, forests, and grasslands along the perimeters of the Australian continent. Being this large of a creature, it would have a very hard time surviving in an area without readily available sources of water.

Hair impressions on fossilized footprints tell us that like wombats, Diprotodon had a dense coat of hair. It was thickly, stoutly constructed, with awkwardly pigeon-toed front feet, armed with large claws that it probably used to dig up subterranean roots.
Superficially, it would have resembled a furry, hornless rhino, with a gigantic noggin and toes instead of hooves. Even more notably, it had large, retracted nasal bones, which seem to suggest either the presence of a fleshy trunk of some kind, or a bulbous, leathery, koala-like, sac-shaped nose. Either way, Diprotodon was bound to be sort of ridiculous-looking to any humans that encountered it as they made their way into the newly discovered continent eons ago.

Like a Muppet…but the size of a mini-van.

A creature so impressively large must have had some sort of cultural impact on the first humans that crossed over from Asia, and many scholars believe that this impact can be discerned today. The ‘bunyip’, a mythological beast that typically is described as a large, billabong-wallowing, generally mammalian animal that’s especially malicious towards humankind, is a cultural item that is common throughout many tribes across Australia. It may be that the mighty Diprotodon has been passed down through the millenia as a cultural memory, transformed into the mythical, deadly, hippo-like bunyip in the folklore.
Some Aboriginal groups, when shown Diprotodon bones, refer to them as bunyip remains. It may be that the bones themselves inspired the bunyip tale, or early humans really did encounter the animal, and pass down the stories for many thousands of years, and eventually these stories were warped into a mythical form by the modern era.

Again, humans are the suspected culprits in this lumbering beast’s ultimate demise, as within a few thousand years of humans’ arrival on the continent, Diprotodon was gone. Diprotodon was probably agonizingly slow, and had no chance against the sharp weapons humans had brought along with them. It was literally a shuffling bag of wool-covered flesh; no defenses, and no offensive capabilities to speak of…save for simply looking silly enough to cause a laughing fit in any would-be hunters.
Another possibility for their extinction, and perhaps more likely, is an indirect effect through the practice of fire-stick farming that ancient Australian aboriginal peoples practiced. Fire-stick farming is the intentional burning of scrubland vegetation to assist hunting practices (cornering animals in a constructed brushfire, or simply burning them alive), as well as to facilitate the growth of edible plants, and the development of ecosystems that directly benefit human hunting and gathering practices. Indigenous Australians practiced fire-stick farming for many thousands of years, gradually turning large areas of Australia into grassland, from native scrubland; evidence for this can be found in the geologic record via a marked increase in the amount of ash and charcoal deposits. It may be that this relatively dramatic, and quick, ecosystem alteration, combined with active hunting of megafauna like Diprotodon, was the cause of such widespread extinction when humans arrived in Australia.

Some people contend that they’ve SEEN weird animals that resemble what Diprotodon is thought to have looked like. Oddly enough, descriptions of these creatures usually change with new revelations on life reconstructions of Diprotodon…funny that.
While very, very little evidence exists that suggests that some small populations of the world’s largest marsupial may still live in Australia, there have been rumors of unidentifiable, bulky, big-schnozed animals being spotted in France, of all places.

Gerard Diprotodieu

Relatively a lot is known about Diprotodon in comparison to the next extinct metatherian I’m addressing; possibly one of the most enigmatic, and historically troublesome, creatures to be unearthed out of the Australian Pleistocene.

This is Palorchestes.

“…’sup brah?”

Palorchestes means ‘ancient leaper’, but judging by the reconstruction above, this animal was probably less into the leaping and more into the getting-baked-and-eating-oreos-with-peanut-butter side of things. Palorchestes‘ story begins with a profound misidentification, and many decades of radical ‘adjustment’ as new fossil evidence trickled up from the rock below.
The famous British anatomist Richard Owen (the same globular-eyed Victorian gent who coined the word ‘dinosaur’) first described fossils of this creature in 1873. Only a meager hunk of bone from the front of the skull was sent from Australia (still very much a part of the Empire at the time) to Owen back in Britain. From this small piece, Owen surmised that it had to be a kangaroo, based on the tooth morphology; not only that, but that it must have been the biggest kangaroo yet discovered…potentially a ten-foot tall giant.
Owen was actually relatively close; Palorchestes does reside in that same big marsupial order of Diprotodontia as kangaroos, and is somewhat related. But, only as closely as koalas, wombats, and the gigantic Diprotodon. In reality, Palorchestes was a distinctly un-kangaroo-like critter, but it would take nearly a century for this information to come to light.

The vision of Palorchestes as a titanic kangaroo persisted for the first half of the 20th century. At the Australian Museum in Sydney, Palorchestes was represented by a towering to-scale sculpture of a 10 foot tall kangaroo for more than thirty years; it was a big hit with visitors, as one can imagine.
Doubts in the paleontology community about the phylogenetic placement of Palorchestes started to swirl about in the late 50s, culminating in a highly persuasive argument put forth by J.T. Woods in 1958 that the animal was definitely more of a wombat than a kangaroo. In response, the Australian Museum trashed their beloved mega-kangaroo sculpture (literally; it’s been said that they shattered it and then buried the pieces) in order to avoid embarrassment.

More fossil evidence turned up in the 70s that showed that Palorchestes in fact had heavy claws on its forefeet, as well as a bizarrely shaped skull and deeply recessed nasal cavity, meaning that it probably had some sort of trunk. Not exactly wombat-like.
Reconstructions varied for the following few decades. It was re-imagined as a lanky, llama-shaped browser, a scythe-clawed piggish looking animal, and finally, as most modern depictions show, a surreal mash-up of a tapir and a ground sloth.

Most modern paleontologists that have studied Palorchestes place it in its own family, distinct from the ‘giant wombats’ like Diprotodon, but most certainly a cousin. Palorchestes, due to the presence of tough, high-crowned, resilient teeth and a flexible proboscis of some kind, and a deep well in the lower jaw for a prehensile, giraffe-like tongue to reside, was undoubtedly a forest and woodland living creature that browsed on rough leaves, twigs, and other hardy vegetative material.
Palorchestes had ridiculously strong, well-muscled forelimbs, and this is especially true in the forearms. When living, it probably looked like it spent every second of free time ripping phone books in half. The combination of all this forearm strength and the five mining picks attached each hand have led scientists to the conclude that Palorchestes was really into excavating.
It could have used these claws for digging down into the soil for roots, or for stripping trees of their bark and exploiting the tender cambium layer, or both. Palorchestes has been described as a ‘tree wrecker’; an herbivore specializing in simply beating the shit out trees by digging out their bases in search of roots and tubers, yanking down branches with its mighty arms, and flaying the poor plant for good measure with its grabbling-hook paws, all the while stripping it of its delicious leaves with its nimble trunk and tongue.

I shudder to think of the dendrocidal atrocities this poor joey has seen…

As is popular with making comparisons between isolated marsupials and their placental counterparts, in order to illustrate the majesty of convergent evolution, Palorchestes was considered a ‘marsupial tapir’ (in much the same way that the thylacine, or Tasmanian tiger, was called a ‘marsupial wolf’) on account of its trunk and browsing way of life. However, it may be accurate to say that Palorchestes was, ecologically, even more strange; more of a ‘marsupial ground sloth’.

Palorchestes never reached the elephantine sizes of their contemporaries, the placental ground sloths of South America, but were large for marsupials, nonetheless. One species, P. azael, was roughly the size of a cow, and could have made short work out of any small to mid-sized tree.

Kangaroos the size of NBA players, wombats heavy enough to launch a Subaru off a see-saw, and the Seussian acid trip that is Palorchestes are all nice…but where are the carnivores? Surely, you ask, with all these big, hulking plant eaters around, there were some badass pouched predators to take them down, right?
Although many of the largest and underwear-soilingest predators were reptiles and birds during the golden age of marsupials in Australia and South America, specifically 20-foot long monitor lizards and long-legged terrestrial crocodiles in Australia and 8-foot tall flightless ‘terror birds’ in South America…there were some opportunities for nasty, apex predators of the metatherian variety to evolve.

And they were horrifying.

One such predator is Thylacoleo of mainland Australia. The genus name means ‘pouched lion’, or ‘lion with a pocket’…which alternatively sounds like a children’s book. Thylacoleo, in the style of the ‘marsupial wolf’ and the ‘marsupial tapir’, has been dubbed the ‘marsupial lion.’ While obviously not actually related to lions, Thylacoleo was so named due to its size and vaguely cat-like shape, and well, the fact that it was incredibly scary looking…

The demonic fucker above is Thylacoleo carnifex…the ‘carnifex’ means ‘murderous’ or ‘meat-cutting’. Not even a joke.
As far as we know, it was the largest carnivorous marsupial that ever lived, and the only one with enough balls to take down a Diprotodon or a Procoptodon.
This is an animal that has given us very complete remains in the fossil record, and yet we still know very little about how it lived or hunted…mostly because it is, quite honestly, unlike anything living.

A huge reason for this is that it is a hypercarnivore with what appears to be the ‘wrong’ ancestry. Every marsupial mentioned so far in this post has been a member of the order Diprotodontia, a diverse order that currently is the most speciose among marsupials and has a even richer history. Diprotodontia houses most familiar marsupial herbivores; kangaroos and wallabies, koalas, wombats, and the Australian ‘possums’ (including sugar gliders). Members of this order are united by unique dental characters, including the presence of just two large procumbent (sticking straight out from the tip of the jaw) incisors on the lower jaw, as well as a lack of canine teeth (there’s a conspicuous ‘gap’ in the mouth where they should be). Most members also have syndactylous second and third digits in the hind feet. ‘Syndactyly’ essentially means that the toes are completely fused together, and while this is a common birth defect in humans, in this group of marsupials, creepy mutant feet are normal. This condition is most easily seen in koalas, which use their fused toes creatively in their climbing technique, but even kangaroos have the feature.

And this little piggy doesn’t understand the concept of ‘personal space.’

With a complete lack of canine teeth, and a mouth instead full of teeth for trimming and mashing plants…it makes sense that for much of the history of the order, Diprotodontia has been an overwhelmingly herbivorous lineage. There are some rogue agents, like the rat-kangaroos like Propleopus and its occasionally insect-munching descendants, but true carnivorous habits were never a real part of the Diprotodont strategy.
The real marsupial ‘carnivores’ of Australia are the Dasyuromorphia, the ‘dasyurids’, which includes the Tasmanian devil, many small insect-eating shrew-like animals, and the extinct thylacine. These are animals with dentition more geared towards processing other animals; sharp canines, meat-ripping cheek teeth, etc.
Ecologically, Diprotodonts are to deer, antelope, and rabbits as Dasyuromorphia are to cats, dogs, and weasels.

So, when I say that a super-predator like Thylacoleo was actually kin to the Diprodontia clade, there’s a smack of incredulity. Finding an animal like Thylacoleo is like finding a sabertoothed zebra in the fossil record…very unusual.

The largest species of Thylacoleo, T. carnifex, could have weighed up to more than 300 pounds and was about the size of a jaguar. Much like a big cat, it was blanketed in rippling muscle, but its skeleton suggests that it wasn’t nearly as fleet over the ground as its placental namesake. To say this animal was robustly built would be an understatement. Thylacoleo‘s skeleton anchored an ungodly amount of muscle, and while this was a critical adaptation for holding down large and difficult prey, it made chasing things with any amount of speed completely unfeasible.
It is thought, instead, that Thylacoleo was an ambush predator; quietly sneaking up on its prey, and then jumping out of nowhere and dispatching it on the spot, using its strength to muscle it to the ground.
And, given the morphology of its feet, this ‘lie in wait’ spot may have been up in the trees. The marsupial lion had very flexible feet, and the front paws had a semi-opposable thumb, much like that of a koala or a possum, which would have both assisted in climbing and holding onto prey. The back feet also had a roughened pad underneath, like a possum, that would have given Thylacoleo more friction when clambering up a tree trunk. The marsupial lion may have actually been more of a ‘marsupial leopard’, stalking prey from high vantage points, dropping down, and then dragging the kill back up the tree to dine in solace.

I can see you wish to eat alone. Pardon my intrusion. Please don’t kill me.

Thylacoleo had a number of superb adaptations for wrestling with large, potentially equally as powerful, prey items. One of them was its tail, which was reinforced with bony chevrons that protected blood vessels and nerves in the event that it had to rear up on its hind limbs to give its next meal a less-than-friendly final embrace, potentially propping itself up on its tail, kangaroo-style.

Another, far more obvious adaptation, as you’ve likely noticed by now, was on those lovely hands. Thylacoleo‘s unnervingly primate-like thumb was dramatically oversized, and came equipped with a truly heart-stoppingly giant claw. It’s other claws, also quite sharp, were actually retractable to avoid wear and tear, much like a cat’s claws; this trait is found in no other marsupial. However, the Big One was out and about, and its function is not entirely clear.

My guess? Convincing every animal on the continent to do whatever the hell Mr. Thylacoleo wanted.

At first, it was thought that the marsupial lion used these tools as killing weapons in themselves. It was imagined that Thylacoleo would rear up on its haunches, and basically shred the fuck out whatever was unfortunate enough to look tasty that day, disemboweling it before it even hit the dirt. However, many scientists have moved away from the ‘Slice ‘n Dice Katana Hands’ theory for something a bit more probable, honestly; that Thylacoleo used the claws both as a means to simply dig into its prey while it struggled, and as a way to increase its grip as it ascended and descended from trees…possibly while carrying hundreds of pounds of fresh kill.

If the idea of an animal with built in grappling hooks, evolved specifically to keep you from squirming away from its hungry stomach, wasn’t enough to send a river of urine down your leg…well, take a look at the head.

Fucking Christ.

You’ll notice that the marsupial lion’s skull doesn’t look a whole lot like other carnivores, like dogs, cats, bears, etc. And that’s to be expected, since Thylacoleo‘s evolutionary trajectory is vastly different.
The skull of this creature is superb example of how evolution ‘makes due’ with the starting materials. How do you make a mammal without any canines, that is part of a long lineage of herbivores, into a damned beast slayer? Evolution answers this question through improvisation, and it in the case of Thylacoleo it turned out elegantly.
In placental carnivores like big cats and wolves, those canine teeth are crucial. They serve as deep grip when the predator is crunching down on the neck of its prey, and they provide  some ability to rip and pull at the meat once the prey item has been killed. The numerous little peg-shaped incisors in the front help with this too, and the back cheek teeth are narrow and sharp for shredding the meat into ribbons before it’s swallowed. In these animals, there is a concert of teeth working together and in an assembly line.
Thylacoleo, being a Diprotodont, doesn’t have this diversity of teeth, so instead, the two pairs of front incisors have become pseudo-canines. They tilt towards each other to form a sharp ‘beak’, which quite effectively penetrates soft giant wombat flesh at the very beginning of the bite. Immediately, following that, the mouth itself has evolved to drag the entirety of bulk of the animal back into the throat of Thylacoleo with the closing action of the jaw.
What this does is automatically place the flesh between the pairs of dramatically enlarged, sharpened premolars in the middle of the mouth, where it gets cleaved. These huge premolars dominate the mouth of Thylacoleo, and are among the most specialized carnivore teeth ever seen in animals alive or extinct. As the mouth closes, the curved, bladed surfaces of the premolars form complementary crescents that narrow until the teeth slide past each other. In essence, they work together like biological shears, cleanly slicing off mouthfuls of meat, bone, and cartilage in a single go.

The effect of these perfectly constructed teeth is enhanced, of course, by the sheer force by which Thylacoleo can bite down. As you can see above, there is plenty of broad, thick, sturdy bone for muscles to attach to on that head. The amount of muscle hanging off the jaws of the marsupial lion, proportionally, is unprecedented in mammals, even when compared to modern big-biters like hyenas and ‘real’ lions. Biometric studies of the skulls of even small Thylacoleo specimens show that they would have been able to crunch down on prey with the equivalent bite force of a lion or tiger well over twice their weight. A 220 lb marsupial lion could easily outperform a 500 lb African lion in a bite force test. In fact, Thylacoleo possessed, pound for pound, the strongest bite force of any mammal.

Thylacoleo‘s killing strategy would have stood in stark contrast to the placental big cats it resembled. Tigers, lions, and leopards grapple their prey, and then clamp down on the jugular with an array of sharp teeth until the animal suffocates or bleeds out, usually over the course of a long, arduous dying process. Thylacoleo would have been an animal that wasted very little time. After an initial take down, those powerful jaws would dive in, plunging through flesh and bone like great bolt cutters.

Lions and tigers pin, maul, and bleed their prey to death. Thylacoleo probably could have decapitated its prey if it wanted to.

The marsupial lion was a nightmarish blend of jaguar, steroids, a deli cutter, and a Velociraptor, all perfectly assembled into one brutal bastard of a marsupial.
The combination of the deadly jaws, highly-derived teeth, thumb claws, and strengthened tail bones have led many paleontologists to conclude that despite its herbivorous pedigree, Thylacoleo is likely the most highly specialized carnivorous mammal ever. For being a ‘primitive’ marsupial, that is quite the distinction.

However, its excessive specialization may have contributed to its extinction. It too died out right around the time humans made their way into Australia. Humans probably did interact with Thylacoleo, as the following cave painting suggests:

While humans may have met up with marsupial lions, it is doubtful they killed them directly, and especially not for food. Thylacoleo would have laughed off a spear, and followed up by swatting the limbs from your body in anger. It is very likely that early Australian aboriginals gave Thylacoleo a wide berth, and it is possible that humans were specialty items on the menu more often than not.

What’s the last thing you’d want to see in Australia, 50,000 B.C.? Survey says ‘a Thylacoleo looking down at you and licking its lips.’

Instead, humans likely precipitated the extinction of the marsupial lion by killing off all its prey. Once big, lumbering Diprotodonts like the giant wombats and short-faced kangaroos were gone, Thylacoleo‘s relatively limited career of taking down larger animals would be over. Australia was hit by a blitzkrieg of highly intelligent, resourceful predators that invaded from a foreign land. It is no wonder that widespread ecosystem disruption was a consequence a short few thousand years after our kind got there.

As I’ve said before in this post, Australia was a roiling cauldron of metatherian evolutionary experimentation…but to some extent, so was South America. South America was a far more wet and forested place for much of the 65 million post-dinosaurian years than Australia, which progressively dried out until the majority of the continent was a single desert. This allowed for the proliferation of different types of endemic metatherians evolved to occupy very different niches from those found on the big, dry island across the Pacific.
Fundamentally, South America was a dramatically different place, with a different natural history. There was an established placental mammalian presence in South America, made up of weird groups like the now-extinct ungulates the ‘litopterns’ and their relatives, as well as ground sloths, giant armored glyptodonts, and very, very large rodents. So, metatherians couldn’t just run wild, evolutionarily. Many of the top predator niches in South America were occupied by the fantastically, and appropriately named, ‘terror birds’; massive flightless relatives of the rails that were the dominant predator group for 58 million years on the island continent.

One radiation of metatherians in South America was particularly successful at competing with the ‘terror birds’ in predator niches. While up until now I’ve been solely speaking of ‘crown group marsupials’, there actually used to be other metatherian groups that split off the main line early in metatherian evolution. These groups are all extinct now, and the only metatherians we can see today are ‘true’ marsupials, but one group, the Sparassodonta, reigned in South America up until a few million years ago.

The difference between sparassodonts and marsupials is mostly one of semantics, phylogeny, and technicality. Sparassodonts had many of the same features as marsupials, and definitely still gave birth to underdeveloped young and had pouches and all of those things. Mostly, the distinction is made because sparassodonts split off from the line gave rise to all the marsupials we know and love significantly early on. For this reason, while they can be thought of as ‘marsupials’, this isn’t technically true…and this is why I entitled this post Metatherians and not just Marsupials.
Calling a sparassodont a marsupial is a bit like calling an alligator a lizard. Not really true at all, although they generally share a lot of the same characteristics, physically.

Sparassodonts are not well-understood. For many years, they were considered to be a part of the Didelphimorphia, the purely South American radiation of ‘opossums’, as they had some morphological similarities. Many of them were vaguely dog-like, but also had nimble, climbing-adapted digits and semi-opposable thumbs. They were exclusively carnivorous, and the image of Sparassodonta being a lineage of giant, predatory opossums made sense…and let’s be honest, it sounds badass.
But, later studies have placed Sparassodonta as a separate metatherian entity, and currently they rest as stem-marsupials at best.

Many Sparassodonts were lean-snouted, weasel or dog-like predators, but there was quite a bit of diversity within the order, especially later on, during the Pliocene epoch (between about 5 and 2 million years ago). For example, there were the highly successful borhyaenids, which were short-legged, and yet often bear-like, bone-crushing monstrosities. And, most notably, there were the thylacosmilids…the ‘marsupial sabertooths’.

Thylacosmilus atrox, the largest and most well-studied member of the ‘marsupial’ sabertooth family is an eerily textbook example of convergent evolution. Convergent evolution refers simply to two or more groups of organisms evolving the same trait despite having differing lineages. An often used example of this is a comparison between the body shape of dolphins, sharks, and the extinct icthyosaurs. Dolphins are mammals, sharks are fish, and icthyosaurs are reptiles…and yet they have all converged on the most efficient body plan for being fast predatory animals in the water; streamlined body, rigid pectoral fins, tail flukes/fins, and even a dorsal fin. Gliding membranes have developed independently in flying squirrels (rodents), sugar gliders (marsupial possums), and colugos (primate-like animals in Southeast Asia). There are multiple extant groups of ‘anteaters’ and ‘termite eaters’ that all have similar adaptations (long snouts and tongues, reduced teeth, strong clawed forelimbs); true anteaters of South America, pangolins in Africa and Asia, numbats (marsupials) in Australia, aardvarks in Africa, echidnas in Australasia, armadillos in the Americas, and the sloth bear of Southern Asia.

Convergent evolution runs rampant on our planet, funneling organisms into the most efficient forms for a given occupied niche. The sabertooth strategy (precise laceration of major arteries using huge, fragile canine teeth) sits at the bottom of one of these funnels, as there have been sabertoothed cats, ‘false sabertooth’ nimravids (somewhat close relatives of cats), reptilian ‘gorgonopsids’ that pre-dated the dinosaurs, and of course…Thylacosmilus…the ‘pouched saber.’

Thylacosmilus was roughly the same size as a small lion or a jaguar, essentially tying with Australia’s marsupial lion for the title of largest metatherian carnivore ever. With a long, supple body and broad paws, it probably looked superficially cat-like…likely even more so than the marsupial lion. However, it lacked the retractable claws found in cats, and with its semi-opposable thumbs on the front feet and plantigrade (meaning that when walking, the whole foot presses against the ground, not just the toes, as in cats and dogs, which are ‘digitigrade’) locomotion it wouldn’t have the same ‘spring’ in its step. It likely plodded along silently and cautiously, not unlike the carnivorous opossum it was first suspected of being.
Due to its feet, as well as its generally short legs and thickly muscled body, the marsupial sabertooth, like the marsupial lion, was not built for running down prey, and was also a likely ambush predator.
It’s important to note that ‘real’ sabertooths are thought to have the same hunting strategy, as they were also too bulky to chase down prey for extended periods like a lion or cheetah.

When one gets to the head of Thylacosmilus, what at first seems to be a normal carnivore skull starts to morph into something far stranger.

There is a lot going on that is…’off’…with the head of Thylacosmilus.
First, those impressive saber teeth. Unlike ‘true’ sabertooths, the sabers of the ‘marsupial’ sabertooth grew throughout its lifetime, a bit like the teeth of rodents. Thylacosmilus had invested so heavily in this particular sabertooth-based killing strategy that the teeth had literally reshaped the skull of the animal, turning it into a misshapen hunk of bone. The saber teeth were so far embedded in the skull that the roots in the maxillae had extended up past nasal cavity, and up above the eyes and above the braincase…giving Thylacosmilus a curiously convex dome between its eyes. The intrusion of these teeth was so extensive that it obliterated any attachment points for any of the front top incisors, giving the marsupial sabertooth a decidedly unthreatening gap between its gigantic sabers.
Unlike many placental carnivores with saber teeth or powerful bites, there was no sagittal crest (a ridge running down the skull that allows jaw muscles to attach) on top of the skull. Instead, the back of the skull was a knotted burl of protuberances that provided muscle anchoring points that likely gave Thylacosmilus and impressive enough bite, but also, and more importantly, flexibility, strength, and finesse in the neck, as sabertoothed animals drive the force of the piercing blow from the neck and shoulders, not the bite itself.

Perhaps most strikingly were the two bony flanges running down the sides of the jaw, corresponding to where the sabers would lay when the mouth was shut. These would protect the delicate teeth by providing extra support in the event a substantial force hit the tooth from the side.
Yes. Thylacosmilus had goddamned biological scabbards for its saber teeth growing from the sides of its face.

Thylacosmilus also had somewhat smallish eyes completely encased in a ring of bone, which is very different from the cradle in which placental carnivore eyes sit.

Humans never saw this odd animal, as it is thought to have gone extinct shortly after the Isthmus of Panama formed, causing the Americas to be joined for the first time in tens of millions of years; this happened about two million years ago, long before our species even existed.
The result of this joining of two very different lands was the Great American Interchange, in which various groups of organisms invaded/migrated across the isthmus, dramatically impacting ecosystems on either side, and forever changing the biogeography of the Western Hemisphere. Ground sloths, terror birds, porcupines, and armadillos invaded from the South. Otters, tapirs, horses, camelids (llamas, etc.), condors, and wolves invaded from the North.
Also along with the migration from North to South America were the sabertoothed cats.

It is thought that the extinction of Thylacosmilus was the direct result of sabertoothed cats like Smilodon coming into South America and completely outcompeting it by occupying precisely the same ecological niche. Two predators with the exact same hunting strategy, targeting the same types of prey, and utilizing the same tools, cannot coexist for long.
Why Thylacosmilus potentially lost out in this competition is unknown, but it may have something to do with all that specialization surrounding the saber teeth.
Thylacosmilus put all its evolutionary eggs in one basket; those perfected fangs. It invested so much into the saber teeth that it sacrificed any additional expansion of the forebrain because the roots of the fucking teeth were in the way. It’s possible that Thylacosmilus simply didn’t have the brainpower to compete against a predator like Smilodon, and the once grand advantage of having expensive, well-designed killing tools became a species-ending hindrance.

Specialization can only be supported in stable ecosystems. As soon as things change, it is always the species that are most burdened by their own perfected adaptations that perish.

This is partially the lesson all of these extinct metatherian megafauna had to learn. They were superbly adapted to their environments. Pouched perfection. The culmination of more than 120 million years of mammalian evolution. All of that crumbled when the floodgates were opened, and alien invaders, whether they were sabertooth cats or humans, swept in and ruined the party. But, this is how extinctions tend to happen on Earth. Lineages reach the dizzying heights of diversity and specialization, catastrophe hits, and it’s all over, and a new set of players takes up the mantle of the old ecosystem.
Although we lost some amazing, terrifying, and dumbfounding metatherian creatures to the permanence of extinction, there are still plenty of intriguing pouched animals alive today…and many of them go equally underappreciated as their long-gone megafaunal cousins…

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.



We’ve known them as ancient, mythical, winged, pyromaniacal reptilian beasts with a flair for the dramatic and destructive. They have been a fixture in our lore, in some form or another, the world over. While most of these tales of dragons are fictional, or at least highly embellished, there is still a very strong chord of truth in them. The blaze-setting, screeching hell-drakes so common in storybooks have not existed for a very long time, and it is unlikely that Medieval humans actually had contact with them (this stands in contrast with unicorns, which went extinct in 1982 when the last specimen escaped from her enclosure and ingested some antifreeze). However, dragons have had a rich and colorful evolutionary history that dates back 225 million years, and their unique biology and rise and fall in biodiversity is worth discussing.

The earliest known ancestor for the dragon lineage (otherwise known as the order Daemovespera, or ‘demon bats’), is the basal archosaur Postosuchus.

That is quite the disconcerting smile there, friend.

This animal may have looked like a skinny-legged T-rex with horrible posture, but it predates tyrannosaurs by quite a long ways in geologic time. It was a rauisuchian, a member of a group of reptiles that lived approximately 200 to 250 million years ago which eventually gave rise to modern crocodiles and alligators via a splintering sister group. However, back in the Triassic, rauisuchians were much more diverse, and had many apex predators among their ranks. While most of them were out-competed by their dinosaurian cousins by the Jurassic period, some (like the ancestors of crocodilians) and the proto-dragons, flourished.

Postosuchus was a wickedly powerful macropredator of the tropical Triassic forests of Texas. It was as long as a Ford Expedition, and probably weighed as much as a grizzly bear. Also, it had a skull that looked like this:

The dentition shows clearly that it had a diet primarily consisting of babies.

Ol’ Posty also had the distinction of being one of the largest and meanest bastards in its ecosystem, and could quite easily take down just about anything it wanted. At this point in time, most early dinosaurs were scrawny, turkey-sized pipsqueaks, and likely served as food for their knife-mouthed cousin. Postosuchus ruled with a scaly fist, and I mean that quite literally, because this creature was probably among the first archosaurs to experiment with bipedalism, and actually had fists.
Postosuchus had front limbs that were much smaller and shorter than its back limbs, which would indicate that it at least had ability to rear up and bring its terrifying face even higher off the ground. However, its hind limbs didn’t have nearly the type of strength or musculature seen in truly bipedal archosaurs, like dinosaurs, suggesting that if it could walk on its hind legs, it couldn’t do it for very long. There is some disagreement among paleontologists on how much this animal could take moving around on its haunches, but it seems likely that it engaged in both types of locomotion, alternating between galloping around on all fours with its ass high in the air, nose in the dirt, eyes menacingly focused on its prey…and as an ungainly, pillar-erect dino-gator, storming through the brush, making every animal in the forest defecate itself in fear.

This experimentation with bipedalism is important, as it was from Postosuchus that later rauisuchians, increasingly more bipedal, had their front limbs free from the role of locomotion. As the Triassic progressed into the Jurassic, and dinosaurs rose to dominance, it was the slow, lumbering, quadrapedal archosaurs that met their demise because they couldn’t cut the evolutionary mustard. However, the two-legged, T-rex-esque offshoots of the Postosuchus line were able to compete in many different biomes. Millions of years ticked by, and they spread from proto-North America, across the northern supercontinent of Laurasia, and diversified, occupying territory that would become Europe and parts of  Asia as plate tectonics shifted continents around along the surface of the Earth.
Many of these predatory creatures, now with their hands free, are thought to have used them for grasping prey much like their dinosaur relatives. Some smaller, sinewy clades, living in the tall coastal forests around the supercontinent, also began using their clawed forelimbs for climbing into trees and hunting the animals that lived there. These arboreal reptiles, some as small as cats, and others the size of bears, proliferated and dominated a lifestyle that no other reptilian had attempted yet.
By the end of the Jurassic, predatory theropod dinosaurs, the likes of Allosaurus and Saurophaganax, had become large, fast, intelligent, unstoppable killing machines. Some reached lengths of over 40 feet and weighed several tons. The big bipedal rauisuchians were limited by their inefficient, crocodile-like ankle structure, and couldn’t develop the swift athleticism or size common to the dinosaurs with which they were competing for territory and food. So, this group began dropping like flies.
But, their tree-dwelling hippie cousins in the forests bordering the shorelines were expanding and diversifying, and some groups were evolving new prey-capturing tricks. The first of these new abilities was stereoscopic vision (evidenced by forward facing eye sockets), which allowed the depth perception required for scampering around in the canopy and targeting food. The other new trait that had become a successful tool in the trees was the use of fire.

Roughly 160 million years ago, one group of tree-dwelling proto-Daemovesperans inhabiting the tropical islands of what would eventually become Europe, developed the fire-breathing trait. It began when this lineage evolved a symbiotic relationship with several species of bacteria in their gut. This relationship first developed due to the selective pressures associated with eating heavily armored tree-dwelling reptiles. There were many species of thickly armored, arboreal lizards that made their residence in the pre-European island chain. The plates on the outsides of these creatures were too tough to digest for the early dragons, but since the armored animals were plentiful, any creature that could successfully eat them would have a significant evolutionary edge. So, it was a mutant offshoot of the tree-dragon line that had a close association with bacteria in a special pouch at the front of its digestive tract that received this boost. The bacteria produced sulfuric acid, which, combined with the specially adapted stomach lining of the dragon, made digestion of these armored reptiles possible. Over time, it was this subgroup that supplanted the rest of their relatives on the islands.
One by-product of this symbiotic relationship was the production of hydrogen gas as waste. For millions of years, it was likely belched out harmlessly throughout the day. However, one group that began deviating away from the exclusive diet of tough, plated reptiles began co-opting this special waste product for its own use. Many species in this particular group were very small, gracile creatures, and were often food for their larger relatives. As a means of deterring and startling predators, they evolved a reinforced sac (evidenced in the fossil record by ossified struts extending from neck vertebrae) from the bacterial pouch that connected to the esophagus via a stout valve. This organ, housing the precious bacterial culture, produced and housed large amounts of pressurized hydrogen gas, which would be rapidly expelled from the mouth in the event of a threat. This giant, deafening burp, possibly combined with brightly-colored skin flaps around the mouth, was usually enough to confuse a predator long enough for the attacked to escape.
It wasn’t long for subgroups of this ‘gas dragon’ group to start using the hydrogen organ (also known as a ‘tank’) in creative ways. The most important development came in the ingestion of inorganic platinum from cliff-side rocks which were chewed up and swallowed. We can see this in the fossil record through the presence of platinum-rich deposits in the skulls of these animals, as well as tough, wear-resistant teeth, often also capped with platinum deposits. The combination of the sulfuric acid from the tank, and the hydrochloric acid in the stomach, gave the digestive system of dragons an enhanced punch; the combination of these acids, a mild form of ‘aqua regia’, was capable of dissolving many types of metals, including gold and platinum.
This metallic platinum was distilled in the gut from chewed up rocks, and incorporated into an ossified sheath surrounding cartilaginous projections off the back of the mandible. These projections, capped with a bony shell, were formerly used in communication in more social, intelligent species; screeching or roaring could accidentally expel precious hydrogen, but the clicking of the ‘clackers’ in the back of the throat could be used as vocal communication quite easily. When a platinum layer was infused on the surface of these clackers, they could be rubbed together with great force, and the friction could produce a spark. In the presence of a jet of hydrogen gas expelled from the tank, that spark, catalyzed by platinum and hydrogen’s special chemical relationship, would produce a hot flame plume, the mechanism working similarly to a flint lighter and a Bunsen burner.

This new tool was incredibly useful for defense against larger tree-dragons, as well as for sniping and roasting animals from across the tree branches (which also incidentally caused wide-spread forest fires; it is thought that the evolution of fire-breathing dragons served as one of the first selective pressures for fire-adapted vegetation). As fire-breathing dragons rose in dominance, and other tree dragons went extinct, the islands of Europe began coalescing, and these animals started diversifying as their environments changed from coastal forest, to variable landscapes of mountains and deserts. Many of the species that congregated around exposed cliffs to ingest platinum began to fit into an even more intense climbing lifestyle, and never left the sides of the cliffs. Some are thought to have even evolved large bits of webbed skin that stretched between their front limbs and their flanks. This would have allowed them to effortlessly glide on the wind between cliffs. Over millions of years, in some lineages, this transitioned into full-sized wings developed from the front limbs. By the start of the Cretaceous, the face of the dragon was one with powered flight and the ability to scorch the earth at will.

For the next 80 million years, dragons proliferated as they filled the skies and left their forming European subcontinent, spreading to almost every corner of the globe. They grew in size, and their tank organs became even more specialized and hardy, increasing in size to fill the entire gullet of these animals. Because of this expansion of the hydrogen tank, dragons became especially vulnerable to lightning strike; a bolt of lightning to hit a dragon would invariably kill it, as the hydrogen tank would ignite and the beast would explode in a fiery ball of intestines and bone. Dragons openly competed with many of the now highly-specialized dinosaur groups, and some were even large enough to hunt and kill various dinosaurian species. They became the largest animals of the skies, and over tens of millions of years, dramatically reduced the diversity of the pterosaurs sharing the skies with them.
Included below is a phylogenetic tree showing some of the relationships of the groups of dragons to arise in this period of time:

A larger version can be found here: Bingo

About 65 million years ago, when dragons were at the height of their diversity, they suffered the tragedy of getting slammed in the face with a giant asteroid. Most species, along with all the large animals on Earth, including dinosaurs, went extinct in the fiery, ashy  aftermath. However, some smaller, more generalized species made it through the extinction event, and wheeled around in the skies for many millions of years after that, just as mammals were beginning their own Age. Dragon diversity never recovered from the event at the end of Cretaceous, and as the climate began to dry and cool around 20 million years ago or so, various once-terrifying families of dragons began to fade away. Oxygen levels in the atmosphere fell from Mesozoic levels, and the oxygen-hungry, high-metabolism flying dragons no longer became physical feasible. By the time first Ice Ages rolled around, the few remaining lineages of dragons were greatly reduced in size, flightless, and scattered around the planet in isolated locations where they survived as ‘living fossils’. Repeated glaciations during the Ice Ages did many of these species in, but even today, two relict, distantly-related dragons still exist.

The first of these is the famous Komodo dragon (Varanus komodoensis) of Komodo Island in Indonesia. They are known as the largest lizards on the planet, but in reality, their namesake is a far more accurate declaration of their phylogenetic relationships with other reptiles, as they are relatively diminutive, flightless members of the Pyrospira suborder of dragons. These animals are the size of crocodiles, but far more nimble on land, and thus, much more capable of dragging a small child off into the scrub before you can say ‘fast food.’ While Komodo dragons no longer have the ability to produce flame, and have lost completely their clackers in their throats, they are the top predators in their island ecosystem, routinely taking down adult oxen and anything else stupid enough to share the dirt with these sickle-clawed nightmares.
It was not very long ago that one the Komodo dragon’s close relatives, one that miraculously still possessed the fire-breathing trait, existed in nearby Australia. This relative, Megalania (Varanus prisca), formerly known as Megalania prisca, lived up until about 40,000 years ago in the grasslands of Australia. Hoardes of dragonslayers crossed the land bridge from Southeast Asia into the continent and killed every last one of them over the course of as little as two or three thousand years.

“I’m not trying to eat you! Run! The humans will get you too!”

Megalania was much larger than its Komodo dragon relative. Long enough to have difficulty fitting in your living room, and tall enough to look you squarely in your gooshy, defenseless belly full of viscera, Megalania had a broad skull as long as your arm, equipped with iron strong jaws and sharply hooked fangs. Megalania weighed as much as your Camry, but had better acceleration over open ground. Megalania dominated the Australian outback for millenia, tossing giant marsupials the size of rhinoceroses around like rag dolls and generally just being a belligerent dick.
Most people are not aware of the fact that Megalania was a being that could eject flames from its blade-toothed face…because apparently it just wasn’t horrible enough. It would cook emus and other giant flightless birds like outsized rotisserie chickens on the hot plains, charring the landscape as it did so. In fact, Megalania’s flamethrower habits were enough to cause regular, widespread wild fires all over the Australian countryside. Eucalyptus woodlands were, at any time, susceptible to being torched by any given uncaring, Smokey the Bear-enraging Megalania in search of a quick meal. Sometimes, just because they were cruel, Megalanias would team up and intentionally burn down entire forests, just so they could catch any animals inside that were too slow to get out of the way, and dine on their medium-well remains as they passed through.

No rules. Just right.

Humans haven’t slain the remaining populations of Komodo dragons yet, but if they did, I wouldn’t deny that being a wise decision. Instead of deadly flames, Komodo dragons are in possession of something equally as deadly, but just more intimate and gross.
The saliva of Komodo dragons is laced with a toxic cocktail of venom extruded from glands in the jaw, as well as massive colonies of bacteria picked up from whatever dead animal the dragon happened to tear apart that week.

Good god. Stop it. It’s only cute when a dog slobbers like that.

A single, wet bite from a Komodo dragon can put down any large mammal in a matter of a day (including humans), due in part to sepsis induced by the bacteria, and the debilitating effects of the toxin on the neural and muscular systems. In fact, this is the highly efficient means by which this little dragon hunts large, powerful prey. Bite once or twice, let the animal break free, and then wait for it to tire and succumb to infection and weakness, following it through the tropical forest with a keen sense of chemoreception on a long, forked tongue. Biological excellence, my friends.

The other surviving dragon is also found in the region; in the deserts of Australia. It is the bearded dragon (Pogona), and while it is very small (only weighing up to a pound or two), it packs a rarely observed wallop.
Bearded dragons are popular in the exotic pet trade, and make beautiful and easy to care for reptilian companions. Their ‘bearded’ description comes from the spiny scales around their throat, which upon expansion of the skin in a threat display, resembles a thick, manly, imposing ring of epic facial hair…which, like real hair beards, is enough to stop enemies in their tracks.

“You….shall not….pass!”

Bearded dragons are popular as pets for children because of their easy temperament, but underneath that adorable, friendly exterior lies the heart of a mythical killer, conserved in the genetic code for hundreds of millions of years.
The old behaviors of munching on rocks for platinum are long gone in bearded dragons, but if given platinum-laced food, their almost vestigial clackers will begin to accumulate a platinum coat. Within a few weeks, they may begin to produce short, accidental ignitions. Bearded dragons are omnivores, and can’t hunt anything bigger than a fat grasshopper anyways, so their superheated belches are never used aggressively, but are simply a quirky carryover from their illustrious genetic past. Platinum-fed bearded dragons are usually, wisely, kept in special fireproof cages as to reduce the risk of fire hazard, and are typically kept out of the hands of anyone not wearing protective clothing. Uses for these pets are few and far between, due to the fact that the flames ejected from these little guys usually produce more detrimental risk or injury or liability than benefit. Some exploit their platinum-fed dragons as party curiosities, or as a way to pick up women. Because everyone knows that women love cute animals, especially those that can be trained to toast bread in the mornings.

The lack of thumbs makes it hard to add butter and jelly though.

The humble bearded dragon is quickly replacing the ‘tiny dog’ niche in Western society, and pet accessory companies are beginning to churn out little sweaters and other clothing for these easy-to-freeze animals. It won’t be long before bearded dragons are found clinging to the insides of purses and wearing ridiculously large sunglasses for comedic effect. The only difference, thankfully, is that bearded dragons don’t yap incessantly at everything within 20 yards of themselves.
Some have already taken the initiative to start taking their bearded dragons on walks, as terrariums are cramped and boring. Bearded dragons are naturally athletic animals, and enjoy bounding around on the lawn or sidewalk and exercising their muscular, albeit stubby, legs. Given their regal genetic history, I can’t help but wonder if some part of them finds this treatment insulting to their dignity, if they realize how far they’ve fallen.

How to Demean Your Dragon

So the monsters of lore are gone from us, despite a grand and heart-scorching tale of evolutionary ingenuity and might. All that remains is a disgusting carrion eater the size of a deer, and a chunky, scruffy-faced Aussie lizard that under the right circumstances, might be able to light your cigar for you.
Embrace the fact that you don’t share this planet with the extinct, flying terrors of the Mesozoic. Things would be a lot harder for you, I can guarantee it.

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.