Pseudoscorpionida

Pseudoscorpionida, commonly called pseudoscorpions, are an order of small arachnids that resemble miniature scorpions but lack the elongated tail and stinger. They are one of the earliest diverging chelicerate lineages, and roughly 3,000 described species inhabit a wide range of habitats.

Adults typically measure 2–8 millimeters. Their bodies are flattened and pear-shaped, with the posterior part tapering. The pedipalps are large and crab-like, bearing pincer-like chelae used to grasp prey or mates. Most species have vestigial eyes or are eyeless; they rely on tactile and chemical cues to locate prey.

Pseudoscorpions occur worldwide, from leaf litter and under stones to the bark of trees and caves; many species are also found in human dwellings, in books, clothing, or stored goods. Some species are phoretic, attaching to insects or vertebrates to disperse to new locations.

They are predators of tiny arthropods and their eggs, including mites, larvae of insects, and small insects. They inject venom through specialized glands in the pedipalps, helping subdue prey, while their feeding is primarily on micro-arthropods. Some species may produce silk to construct retreats or wrap eggs in protective cases.

In reproduction, males deposit a spermatophore on a substrate; a female retrieves it to fertilize eggs. Eggs are often carried in a silken sac or brood chamber until hatch. Development is direct, with molts from juvenile to adult stages; many species exhibit some form of parental care for eggs or young. Pseudoscorpions are generally harmless to humans.