Palpigrades, commonly known as microwhip scorpions, are a rare order of tiny arachnids (length 3 mm (0.12 in) or smaller), with a look similar to the whip scorpions (uropygids). Approximately 80 species have been described, in two families. Their abdomen terminates in a whip-like, multi-articulated, bristled telson that makes up as much as half their body length, giving them their common name.
Small, poorly sclerotized and fragile, microwhip scorpions dwell in moist, stable habitats. They are mostly found in warm-tropical environments, but they are reported from every continent with the exception of Antarctica. In Europe, they are known from several caves. They inhabit underground cavities, soil and beach sands.
Little is known about the ecology or lifecycles of the palpigrades. Although generally believed to be predators (as are most arachnids), recent research shows that the European cave-dwelling species Eukoenenia spalaea has comb-like specializations on its large chelicerae which it uses to feed on cyanobacteria rather than miniscule invertebrates (Smrž et al. 2013). Say the authors of this study, “This non-predacious food selection represents an unexpected and extraordinary feeding specialization among the mostly predacious arachnids.”
Palpigradi, also known as microwhip scorpions, are one of the least well-known of all Arachnid orders. There are only 82 known species, but there are probably many more unknown species. The Order Palpigradi are considered to be some of the most primitive arachnids. Palpigradi have "a very distinctive multi-segmented flagellum."