There are some 900 known species of "camel spiders" or solifugids (Order: Solifugae). Solifugid comes from Latin and means 'fleeing from the sun'. They are most abundant in arid climates and range in size from 20mm to 100mm in length. The larger species tend to be nocturnal while the smaller brightly colored species are diurnal. These creatures are also commonly called windspiders, windscorpions, red romans, beardcutters, haircutters, hunting spiders, and sunspiders.

Besides the Middle East, they can also be found in Africa, Australia, New Zealand, and North America (mainly in the desert southwest).

Despite their appearance and their strong bite, camel spiders are not likely to harm humans. They once were considered venomous and extremely dangerous but it is now thought that the only risk of injury resulting from them is caused by shock or infection following a bite. There is no evidence of venom in any part of their body.

When active during the day they avoid the hot patches of ground by running from one shadow to another. In the case of humans (and other large animals) that have a moving shadow, the camel spider repeatedly moves into the shadow. This gives the impression that the animal is chasing the person (or animal) thus camel spiders' moniker "the hunting spider".

Although they may seem fierce and intimidating they perform some good to mankind by keeping scorpion, spider and insect populations in check. They have also been known to eat lizards, mice, small birds, and other smaller animals. They have voracious appetites and will often gorge themselves until they nearly pop.

Sources:
Dippenaar, A. 1993. Sunspiders - some interesting facts. African Wildlife. 47(3): 120-122.
http://ag.arizona.edu/urbanipm/scorpions/solpugids.html
http://insects.tamu.edu/images/insects/fieldguide/cimg376.html