Order: Palpigradi
Known as palpigrades or microwhip scorpions Palpigradi is small order of arachnids that live in wet tropical and subtropical soils worldwide. A few species are also known to inhabit coral sands and tropical beaches. Palpigrades need a damp environment to survive and actively avoid light. And as such they are often found under stones and in moist soil where they are thought to feed on small animals.
Palpigrades are thought to be closely related to the uropygids but much is still known about their biology/taxonomy. Palpigrades are noted for their 15 segment long flagellum which is covered in bristles. Unusually they use their pedipalps for locomotion rather than as sensory organs like in other arachnids. Palpigrade species are diverse in their methods of respiration as some species have abdominal lung-sacs, but most have no respiratory organs and breathe directly through their cuticle.
Phylogeny
Animalia-Arthropoda-Chelicerata-Arachnida-Palpigradi
Images: Rollin Verlinde and Lynn McCutchen
(via typhlonectes)