The Vinegaroon

This alien-looking insect preys upon scorpions and squirts a vinegar-like substance from its tail as a defense mechanism. A vinegaroon is an strange arachnid that resembles its prey, the scorpion, though it is more closely related to spiders. A member of the Thelyphonida order, it is also known as a whip scorpion, due to its thin whip-like tail. Thelyphonida are useful for their predation of nuisance insects, and though a bit terrifying in appearance are harmless to people. They are found in the Southern US, as well as in tropical and sub-tropical regions of South and Central America, Asia and Africa. Sporting a pair of lobster-like claws, called pedipalps it preys on crickets, cockroaches and centipedes as well as scorpions. On the inside surface of the pedipalp is a sharp barb, which the vinegaroon uses to immobilize its prey. Then it crushes the victim with the pedipalp and feasts on the emerging bodily fluids. One of the largest members of the vinegaroon family, Mastigoproctus giganteus, is found in the American Southwest and can be up to 6 inches long. Though whip scorpions have eight eyes, their sight is poor; they hunt mostly by feel, using their long and sensitive front pair of legs to get an idea of their surroundings. The tail is used in this way as well, and is called a telson, as are the tails of shrimp and lobsters which the vinegaroon tail resembles.

Pavel Kirillov. https://www.flickr.com/photos/pasha_k/14538433876

The name vinegaroon comes from the highly concentrated acetic acid spray that the insect releases from glands near the base of the telson. Acetic acid is the key component of vinegar, though the whip scorpion's cocktail is much more concentrated, and also contains caprylic acid and organic solvents in the 2-ketone family. When threatened, it contracts the tail muscles to unleash this mixture up to a foot away, with very precise control of the direction. Besides the noxious smell, the spray is also quite irritating to mucous membranes, so the vinegaroon will aim for eyes, mouths and noses.

The species has an elaborate mating ritual that can last over 14 hours. When a male comes across a female, he chases and tries to overpower her. They grapple and spar with one another, sometimes for hours, to establish the suitability of their potential partner. The female will then either reject the advances by flicking her front legs, or signal her receptivity by sticking them in her partner's mouth and wiggling them back and forth. Next comes an elaborate dance. With her legs still in his mouth (chelicerae), he uses his pedipalps to swing her all around while she follows the lead. WIth her legs still in his mouth, the male maneuvers on top and begins creating a sac of sperm called a spermatophore, which he eventually deposits on the ground. He then thrusts the reproductive material into her gonophore, and spends the next few hours massaging it to help the sperm disperse. Once this long process is complete, they go their separate ways. After several months, the pregnant female seals herself in a protective burrow and lays up to 40 eggs in a broodsac attached to her abdomen. For the whole period she fasts and keeps the sac from touching the ground. When the babies hatch they cling to her for another month, until they develop hardened exoskeletons and begin to disperse and hunt on their own. Finally, the attentive mother is free to crawl out of her burrow and find food.

Vinegaroon preying on millipede.