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.
Palpigradi 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.
Studies have shown that some species feed on heterotrophic cyanobacteria in Slovak Caves – a curiosity among Arachnida.
Image License (credit: Jaroslav Smrž, Ľubomír Kováč, Jaromír Mikeš, Alena Lukešová ; scale removed): Creative Commons