The Palpigradi are very small arachnids looking a lot like tiny Whip Scorpions (Uropygi). They have no eyes and no chelae on their pediplaps. Their abdomen appears obviously segmented and terminates in a thin tail-like 'caudal appendage' of 15 segments, from which they derive their common name. They are widely distributed around the world occurring on all the major land masses except the arctic and antarctic. They are all confined to one family, Koeneiidae which contains 4 genera and about 20 species,
They are distinctly photonegative (meaning they hide away from light) and live under half buried stones and rocks. They are extremely prone to drying out , and are therefore only found in damp areas. They are probably predatory on other very small organisms which share their habitats.