The Solifugae are commonly known as the wind scorpions or the sun spiders. There are over 800 species world wide. They are very fast runners. They are found in tropical and semi-tropical regions, usually in hot or warm arid environments.

They tend to hide under stones or in crevices. Some species construct burrows.

They can reach 7 cm long. They have 1 pair of eyes, huge chelicerae - each formed of 2 pieces. Their pedipalps look like legs, but end in an adhesive organ which aids in prey capture. The first pair of legs is relatively short and not used in running, but more as "feelers".

They will eat anything they can catch.

Females lay 50 - 200 eggs in a burrow.

Order Palpigradi, the microwhip scorpions.

These are all less than 3 mm long. They live beneath stones, in the soil and in caves, and always where there is high humidity. Their exoskeleton is thin and pale-coloured. The pedipalps are used in walking, but the first pair of legs are used as "feelers", and are held off the ground when walking (see Koenenia sp. on the left). They have no eyes. The females lay relatively large eggs.

Order Uropygi, whip scorpions.

There are around 130 species. They are found in tropical and semi-tropical regions. Most prefer humid environments, but a few inhabit deserts. They range in size from 2 - 65 mm. Some have a pair of eyes, others do not. The pedipalps are large, heavy and often end in pincers used in grabbing prey. The first pair of legs is long, and not used for walking, but for sensing and toughing the surroundings.

Most are nocturnal and hide in leaves, rocks, logs, etc. during the day. Usually they are slow movers, walking on three pairs of legs with the first pair of legs and the pedipals held outwards in the direction of travel. When attacked or threatened the animal raises up its rear end and squirts acid out of a pair of anal glands. This acid is strong enough to burn a human skin, and has a nasty odour, which has led to its other common name - the vinegaroon.

Some species have a courtship dance similar to scorpions, during which a spermatophore is passed to the female.

The female hides in a crevice or burrows and lays her eggs which can number 7 - 35. The eggs are relatively large. She attaches them to her body and remains hidden with them until the young have hatched and moulted. Then the female dies and her young disperse. It can take up to 3 years for some species to reach maturity.

Mastigoproctus giganteus, right, is found in the southern U. S. in a band stretching from coast to coast. It can reach 65 mm in length. During courtship the spermatophore is passed directly into the genital opening of the female by the male using his chelicerae.