Pseudoscorpions, occasionally known as false scorpions or book scorpions, are arachnids belonging to the order Pseudoscorpiones, sometimes known as Pseudoscorpionida or Chelonethida. Pseudoscorpions occur in all terrestrial environments from the seashore to the world’s highest peaks. They are generally rather small, with the largest reaching a body length of 1 cm. All are predators feeding on other arthropods such as springtails, flies, beetles and mites. Members of the suborder Iocheirata have venom glands in the chelal fingers (the ‘pincers’) that discharge venom via the finger tip, enabling them to subdue and kill their prey.
They occur in leaf litter, under tree and log bark and under stones. Some species have adapted to permanent life in caves and have evolved impressive troglomorphic traits such as elongate legs, loss of eyes and pallid coloration. Many species regularly undertake phoresy whereby they attach themselves to flying insects, resulting in movement between habitats.
Most pseudoscorpions spin silk via glands located in the cephalothorax that discharge via the movable finger of the chelicerae. Silk is mostly used to spin small dome-shaped chambers for molting, brooding embryos or protection.
Currently there are some 3,700 species recognised globally, grouped in 470 genera and 25 families.