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.