The other whipscorpions

A rainforest vinegaroon (Thelyphonus sp.) from Cambodia. [Canon 1Ds MkII, Canon 100mm macro, 2 speedlights Canon 580EX]

It never ceases to amaze me how excited everybody gets about the prospect of finding life elsewhere in the universe, even if that life is likely to be in a form of thin layer of slime somewhere deep in the rocks, while our own planet is bursting with forms that would be considered figments of drunk imagination, if not for the fact that they actually exist. Among them, few possess a more fantastic combination of features than vinegaroons (Thelophonida), also known as tailed whipscorpions.

The mouthparts of the giant vinegaroon (Mastigoproctus giganteus) from Arizona are an efficient machinery for catching and crushing prey. These arachnids produce no venom, and must rely on their strength alone to overpower their victims. [Canon 1Ds MkII, Canon 180mm macro, speedlight Canon 580EX]

I first saw a live vinegaroon in Arizona. It just happens that the southern US has the world’s largest species; one who also has a strange preference for dry habitats. Normally, vinegaroons have little tolerance for water loss, and most species are found in tropical rainforests. Vinegaroos have poor vision, and thus their picture of the world is pieced together mostly from the input of thousands of chemical, vibrational, and pressure receptors that cover their entire body. The first pair of legs acts as sensitive antennae, smelling and feeling for prey. At the opposite end of the body a long “whip” (telson) constantly scans the world around the animal like a super-sensitive aerial searching for signals from space. It can detect the faintest odors or movement of air molecules that may signify danger, and the sensors that cover its surface send a constant stream of information to the vinegaroon’s central nervous system. If a potential attacker is detected, the animal snaps into action. But rather than trying to use its formidable pedipalps, which can easily crush large prey insects, the vinegaroon engages its chemical warfare.

The “whip”, or flagellum, of a vinegaroon act as an extremely sensitive antenna that collects information about the world around the animal. It its base the pygidium has two small nozzles that spray a defensive acid cloud. [Canon 1Ds MkII, Canon 100mm macro, ambient light]

At the base of the “whip” a small segment known as the pygidium opens up to a gland filled with a powerful mixture of acetic, octanoid, and caprylic acids (the mix contains 83-84% acetic acid, which is also present in vinegar, hence the animal’s common name; vinegar, however, has only 5-8% of the acid.) The moment a threat is detected, the pygidium, guided with the signals from the “whip”, sends a precisely directed acid spray, smack into the face of the attacker. Being sprayed with concentrated, foul-smelling vinegar is no fun, but even worse is the aftereffect – the caprylic acid in the spray, if it lands on an arthropod’s exoskeleton, destroys the lipids that cover its surface, which not only increases its permeability to the vinegar, but also causes accelerated dehydration. To a desert spider or a ground beetle this may mean death. (Thankfully, our bodies don’t have the exoskeleton, and thus vinegaroons’s chemical weapons have little effect on us; after all, we put vinegar in our food.)

A female shorttailed whipscorpion (Hansenochrus sp.) from Saba, West Indies. [Canon 1Ds MkII, Canon MP-E 65mm macro, Canon MT-24EX twin light]

Like their close cousins, tailless whipscorpions, vinegaroons are rather peaceful creatures, with elaborate mating rituals and extensive maternal care. Although they are solitary predators, they are known to share large items of prey, and up to six individuals have been seen feeding at the same time on a particularly large millipede or beetle. Recent phylogenetic work on the relationships of vinegaroons confirms a long-held belief that their closest relatives are tiny, enigmatic shorttailed whipscorpions (Schizomida). They look like ant-sized, pale vinegaroons, but lack the long “whip”. They do, however, employ similar chemical defenses, albeit little is known about the specifics of this behavior.

During their mating ritual the male of the giant vinegaroon uses his large pedipals to gently caress and steer the female. [Canon 1Ds MkII, Canon 180mm macro, speedlight Canon 580EX]

Considering how incredible vinegaroons and their relatives are, it is not surprising at all that creatures in scifi movies often borrow heavily from their morphology. But if there is one thing that is certain, it is that nowhere else in the universe will you find anything like these remarkable creatures.

Vinegaroons use their first, long pair of legs as sensory organs to detect prey. The large “pincers” (pedipals) are mouthparts. (Thelyphonus sp., Cambodia)[Canon 1Ds MkII, Canon 100mm macro, 2 speedlights Canon 580EX]

6 thoughts on “The other whipscorpions

  1. Oh, this was wonderful. For the longest time, when people asked me about my favorite “bug” I had nothing! Love ‘em all- some more than others. However, one day I realized that the first animal I always thought of was the vinegaroon. They are my answer now. A beautiful diamond in the rough. I just love watching them, excavating burrows, cleaning, hunting. Also such a great educational animal ambassador. Preconceived notions, defenses – chemical and bluff display, alternate means of viewing the world are all things that may be addressed. I have used just this one animal as a nexus for hour long presentations. Jeez. Love ‘em. Piotr’s post goes into the archives! Thanks Piotr!

  2. Great story, great photos! Thanks for sharing the details about the camera gear used, I’m always interested in that.

  3. Pingback: Links 10/16/12 | Mike the Mad Biologist

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