Mygalomorph Spiders: Part 1, Tricky Assassins

I’m going to go out on a limb and say that you’ve probably seen a spider before. Well, that is, unless you’ve been living your entire Earthly existence on the barren, ice-blasted wastes of the Antarctic interior…in which case, I don’t have conversations with murderous, shape-shifting aliens, kthnxbai. Spiders comprise the largest and most successful order of arachnids, with nearly 46,000 species living everywhere from rainforest canopies, to scorching desert sands, to pitch black caverns that wind miles underneath the ground. They are exceedingly varied in their lifestyles and habits. Some can glide like a frisbee from high up in trees. Some slink along the surface of standing water, and nab minnows like some kind of mini, eight-legged, catfish noodlin’ Jesus of Nazareth. Some specialize in the most dangerous prey…other spiders…and net them with a toxin-laced phlegm that they spray from their mouthparts.

Yes, with all their diversity and ubiquitousness in both ecological and human cultural settings, spiders are unquestionably the flagship arachnid group (although many other fascinating orders exist; see the first entry in my lesser-known arachnids series for information on the Class Arachnida in general). Whether we love them or hate them, spiders, as a group, are familiar to us, and many people are aware that spiders come in a huge range of shapes and sizes. For example, it is no secret that black widow spiders (various Lactrodectus species) are among the more dangerously venomous species in North America….or, that the fuzzy, hamster-sized tarantulas (family Theraphosidae) are the biggest spiders on Earth. But what is much less widely known is that far more than size and venom differ between tarantulas and black widows.

While it’s perhaps instinctual to think of spiders as existing in a big monolith of vague “spideriness” with minor tweaks on a common, eight-legged theme, spiders actually divide up into distinct groups with important biological differences, the result of deep evolutionary rifts that stretch back hundreds of millions of years. The truth is that there are several very distinct branches of the spider family tree.

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Arachnids: Vinegaroons

This post is the sixth in an ongoing series on arachnids. Previously, this series addressed whipspiders, hooded tickspiderspseudoscorpionsharvestmen and solifugids. Additional posts on other weird, often overlooked or neglected groups of these creepy crawlies to follow. For a related chelicerate, but as far as science can tell, not an arachnid, see the post on sea spiders.

The vinegaroon.

By now, if you’ve been reading my continually-updated series on the underappreciated and less diverse groups of arachnids, you will have been exposed to an assembly of bizarre creepy-crawlies; among them, “headless” hooded tickspiders, library-squatting pseudoscorpions, manic, ever-hungry solifugids, family-oriented amblypygids, and amputation-prone harvestmen. Weird as these groups all are, few compete with the strangeness of the arachnids known as “whipscorpions”, “uropygids”, or “vinegaroons.”

These arachnids are members of the order Thelyphonida, a small group of arachnids comprised of only 100 species, dwarfed by larger orders like the Araneae (spiders, with more than 40,000 species) and the Scorpiones (“true scorpions”, with about 1,700 species). The order used to be incorporated in a now defunct classification known as Uropygi (which also included small, close relatives known as “microwhipscorpions”). “Uropygi” basically means “tail rump” or “tail rear” in Greek, which refers to the arachnids’ curious, thin, segmented “tail” extending from the back of their abdomen. It is this tail, or “whip”, combined with their general scorpion-like body shape, which is key to the origin of one of their common names; the “whipscorpion.” They are also known by their third common name, used frequently throughout the Americas, “vinegaroon”, which alternatively sounds like the most foul tasting Girl Scout cookie ever.


“Oh…oh god. What have I done?”

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Arachnids: Solifugids

This post is the fifth in an ongoing series on arachnids. Previously, this series addressed whipspiders, hooded tickspiderspseudoscorpions, and harvestmen. Additional posts on other weird, often overlooked or neglected groups of these creepy crawlies to follow. For a related chelicerate, but as far as science can tell, not an arachnid, see the post on sea spiders.

The solifugid.

This group of fleet-footed arachnids is known by many names across the globe. Wind scorpion. Camel spider. Sun spider. Sun scorpion. Unintelligible screaming and cursing. All of these refer to members of an enigmatic order of arachnids; Solifugae. The name of this order, derived from Latin, means “those that flee from the sun”, an acknowledgement of their habit of chasing shadows in an attempt to stay cool in their predominantly hot, sunny, and arid native habitats. Despite their frequently used common names which identify them as some sort of breed of spider or scorpion, solifugids (a more accurate identifier of the arachnids within the Order Solifugae) are most certainly a distinct, separate animal from either group. They may have the long, athletic legs and noticeable jaws of spiders (Order Araneae), and the elongated body, coloration, and desert aesthetic of the scorpions (Order Scorpiones), but the 1,000 species or so of solifugid occupy their own lonesome twig on the arthropod family tree. It is generally thought that Solifugae is a part of a larger subdivision of arachnids, called Dromopoda, which also includes scorpions, pseudoscorpions, and harvestmen (daddy longlegs); specifically, combined analyses of the genetic relatedness and shared morphological features of these critters have also linked scorpions, pseudoscorpions, and solifugids together in a grouping dubbed “Novogenuata.” Although, comparative studies on the male genital system have also suggested that solifugids might have a more complex evolutionary history, showing more similarities with mites and ticks in some ways than with their supposed close relatives, the pseudoscorpions. This confusion of what makes a solifugid a solifugid, and its relationship with the rest of the arachnids, would be greatly assisted by fossil evidence, but the fossil record for the Solifugae is pitifully scant, with a few dubious, incomplete, vaguely solifugid-like specimens dating back to about 330 million years ago…and only a few instances of unambiguous solifugids showing up about 300, 115, and 50 million years ago. Most importantly, the earliest stages of this group’s evolution are currently lost to us.

Whatever they are in the grand architecture of the arachnid clan, they are widespread, gravitating towards hot and dry regions of the subtropics and tropics the world over, omitting their presence from only the continents of Antartica and, surprisingly, considering they would fit right the fuck in there…Australia. And wherever they make their residence, they have a very powerful effect on the humans that encounter them, and they have for an incredibly long time. Solifugids, to put it lightly, have an “imposing” appearance and demeanor, with their huge, sharp, pinching jaws, sizable mass, and ungodly overland speed. Consistent first impressions full of everything ranging from a bad case of the all-overs to panicked, wild boot-stomping has undoubtedly earned them immediate recognition as a being assuredly, terrifyingly divergent from other many-legged beasties since antiquity, with the Greeks dubbing the monstrous arachnid “phalangion”, decidedly separate from “arachne”, the spider. More recently, there are accounts of soldiers stationed in North Africa during both World Wars who would pass the time by pitting captive solifugids against each other, or against a scorpion (because why not, I guess), in a fight to the death in possibly the smallest, ugliest, and leggiest gladiatorial showdown of all time.


I’m thinking a 6-inch tall Joaquin Phoenix will give the scorpion a thumbs down.

These brutal spectacles involving dueling “jerrymanders”, another name for the solifugids, were enthusiastically gambled upon, because of course they were. Also, in regards to the aforementioned moniker, if there’s any animal that I could envision being spiritually associated with the deceiptful, ethically impoverished, slimy act of manipulating voting districts, it’s the solifugid…an animal that looks like it would skitter up your leg and chew and burrow its way into your taint if you so much as looked at it sideways.

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Arachnids: Harvestmen

This post is the fourth in an ongoing series on arachnids. Previously, this series addressed whipspiders, hooded tickspiders, and pseudoscorpions. Additional posts on other weird, often overlooked or neglected groups of these creepy crawlies to follow. For a related chelicerate, but as far as science can tell, not an arachnid, see the post on sea spiders.

The harvestman.

In the U.S., Canada, and the U.K. they are generally referred to as “daddy longlegs.” Less often, they are given the name “shepherd spiders”…not because of an adoration of our wooly, farm animal friends, but because their conspicuously long, spindly legs are reminiscent of how, back in the day in Europe, shepherds used stilts to get a better vantage point for watching their flocks…because in those times, people used tools at their jobs that are, today, relegated for the “circus arts” or whatever the fuck the Oregon Country Fair is.

More often than not, we tend to encounter harvestmen in relatively unflattering settings (dusty corners of garages or sheds, beneath untended vegetative landscaping, suburbia in general) and doing unflattering things, like clumsily wobbling off in a direction very loosely resembling “away” from you, teetering along like an intoxicated pre-teen who grew too fast for their coordination to catch up. Within the scope of our lives, harvestmen are no more than the arachnids of unswept places, with vaguely unsettling, Slender Man-like proportions. However, these thread-legged critters are far more interesting and diverse than most of us are aware of, and make up a unique group of arachnids that is regrettably seen as only a curious afterthought amid the dust bunnies and the nooks and crannies of exposed building foundations.

Before addressing these awesome little nuances of harvestman biology, it’s perhaps helpful to get something out of the way: what harvestmen ARE and what harvestmen ARE NOT.

The most important thing to understand from the get-go is that harvestmen are not spiders. They may have the eight, long legs, the roughly circular body suspended in the middle, and overall size and appearance one would associate with spiders, but harvestmen are a different beast altogether. Sometimes, in nature, something that looks like a duck, walks like a duck, and quacks like a duck…is actually a chicken in a Daffy Duck costume. Harvestmen are spiders in the same way that Senator Mitch McConnell is a Galapagos tortoise…through a superficial, yet striking, exterior resemblance and nothing more.

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Arachnids: Pseudoscorpions

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.

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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.

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Arachnids: Amblypygids

Arachnids.

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?

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