Thelyphonida are commonly called whip scorpions or vinegaroons. There are about 100 species in one family, the Thelyphonidae. They are called vinegaroons because they have a pair of acetic acid (vinegar) and caprylic acid glands at the base of the whip-like flagellum. Most species are tropical but the large (7 cm or more) species, Mastigoproctus giganteus, is found in arid southwestern United States. Species of vinegaroons range in size from 2.5 – 7 cm in length.
They have a rectangular carapace and three thoracic sternites (i.e., chitinous plates on the underside of prosoma). They use their raptorial (spiny) pedipalps to capture prey. Their first legs are antenniform legs held in front of the animal as it moves through the habitat. These antenniform legs are covered in sensory setae and function much like an insect’s antennae.
Vinegaroons are nocturnal and are typically found under logs and stones in underground burrows during the daytime. Males deposit the spermatophore on the ground and the animals exhibit complex courtship behaviors in which the male lures the female close to the spermatophore. The female affixes the eggs to the underside of her opisthosoma (abdomen). When the eggs hatch, the babies hitch a ride on mom until old enough to hunt for themselves.