Uropygid

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{{Taxobox | color = pink | name = Uropygid | image = whipscorpion.jpg | image_width = 250px | regnum = Animalia | phylum = Arthropoda | classis = Arachnida | ordo = Uropygi | subdivision_ranks = Families | subdivision = Geralinuridae
Hypoctonidae
Thelyphonidae
Typopeltidae
}}

A uropygid (plural uropygi) also known as Thelyphonida or commonly known as a whip scorpion, is an invertebrate animal belonging to the order Uropygi in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. They are also known as the vinegarone or vinegaroon because when annoyed they can spray a vinegar-like mist.

The name of the order should be properly Thelyphonida (a typified name), because the circumscriptional name Uropygi Thorell 1882 originally includes the "Tartarides" (now Schizomida) and should be used instead for the name of a broader group (which is also a well-recognized clade) including the Thelyphonida + Schizomida.

1 Physical description
2 Behaviour
3 Habitat
4 External links

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Physical description

The name "uropygid" means "tail rump", referring to the whip-like flagellum on the end of the pygidium, a small plate made up of the last three segments of the abdominal exoskeleton.

Whip scorpions range from 25 to 70 mm in length; the largest species, of the genus Mastigoproctus, can reach 85 mm.

Like the related orders Schizomida, Amblypygi, and Solpugida, the uropygids use only six legs for walking, having modified their first two legs to serve as antennae-like sensory organs. Many species also have very large scorpion-like pedipalps (pincers). They have one pair of eyes at the front of the cephalothorax and three on each side of the head. Whip scorpions have no poison glands, but they do have glands near the rear of their abdomen that can spray a combination of formic and acetic acid when they are bothered. The acetic acid gives this spray a vinegar-like smell, giving rise to the common name vinegaroon.

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Behaviour

Whip scorpions are carnivorous, nocturnal hunters feeding mostly on insects but sometimes on worms and slugs. The prey is crushed between special teeth on the inside of the trochanters (the second segment of the leg) of the front legs. They are valuable in controlling the population of roaches and crickets.

Males secrete a sperm sac, which is transferred to the female. Up to 35 eggs are laid in a burrow, within a mucous membrane that preserves moisture. Mothers stay with the eggs and do not eat. The white young that hatch from the eggs climb onto their mother's back and attach themselves there with special suckers. After the first molt they look like miniature whip scorpions, and leave the burrow; the mother dies soon after. The young grow slowly, going through three molts in about three years before reaching adulthood.

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Habitat

Uropygids are found in tropical and subtropical areas worldwide, usually in underground burrows which they dig with their pedipalps. They may also burrow under logs, rotting wood, rocks, and other natural debris. They enjoy humid, dark places and avoid the light.

Families of uropygids include: