Pseudoscorpions are similar in structure to scorpions although they lack the post abdomen and sting. They are distinguished by their minute size and only measure between 1 and 7mm long. Their bodies are flattened in appearance and some species lack eyes. Their claws are large, like those of scorpions, with a swollen "hand" and a moveable finger or digit. They use their claws to climb up hairs of other animals. Although they normally walk forwards, they are equally good at going backwards. Sometimes they are gregarious and found in large groups.
Pseudoscorpions are predators and possess a poison gland at the base of their pincers which they use to anaesthetise prey. They feed on other tiny arthropods such as spring-tails (Collembola ), book-lice (Psocidae ), mites (Acari ) and silverfish (Thysanurana ). Food is digested externally by a fluid poured over the prey and the liquefied remains are ingested by the chelicerae. Pseudoscorpions regularly clean their palps to remove remains of food so that they can easily suck up their next meal through special grooves. Despite their minute size pseudoscorpions demonstrate a tremendous variety and complexity of lifestyle. They have silk glands and construct nests of silk for moulting, brooding and hibernation. Their courtship dances may be very complicated. Females carry their eggs in a brood sac attached to their genitalia and actually provide nourishment in the form of a nutritive fluid which passes to the embryos in the brood sac. Some species exhibit parental care with the young riding on the back of females, but they generally disperse very quickly. The young are identical to adults in all but size and undergo three moults before they are fully grown.
Pseudoscorpions in UAE
Although pseudoscorpions are generally associated with moist habitats such as leaf litter and crevices, the families Olipiidae and Cheliceridae prefer dry habitats and may well occur in UAE. Manhert (1980) identified seven species of pseudoscorpions from the Arabian peninsula, four of them new to science and Manhert (1991) found 12 species from Oman alone. So far only two unidentified specimens have been found in UAE. They were both inside a light trap and had probably been using a fly or large beetle for transport.