Characteristics of Arizona Sun Spiders

Sun spiders -- named such because they inhabit sunny habitats -- live in deserts and semi-arid areas. Approximately 900 sun spider species inhabit Asia, Africa and the Americas; more than 50 of these species inhabit the American southwest. Arizona sun spiders are approximately 1 to 3 inches long, and yellow to tan in color.

Sometimes reddish in color for Arizona specimens, sun spiders have very thick chelicerae on the front of their heads. They use the large pincers at the end of the chelicerae to capture and subdue prey. So far, scientists have been unable to find venom glands in or near the sun spiders’ enormous chelicerae, and they suspect that spiders are not venomous, despite their impressive and intimidating pincers on the front of their heads.

Sun spiders use their long legs to run incredibly fast -- and run faster than most other invertebrates can. Scientists estimate that they are capable of attaining 10 mph in ideal circumstances. This speed helps sun spiders to capture their prey, which includes insects, spiders, scorpions and the occasional gecko. Additionally, some sun spider species live in or near, and predate on, termite colonies.

Behind the pincers and chelicerae of sun spiders, lay a pair of pedipalps. Pedipalps are important organs that serve both tactile and olfactory functions. When running, sun spiders often hold their pedipalps high off the ground. Sun spiders are also covered in short, bristle-like hairs that detect and transmit other stimuli.

Most sun spiders are nocturnal; they spend the days hiding from the hot sun in their relatively cool burrows. They may dig 40 or more burrows in their lifetime; however, they lack significant physical adaptations for digging. Sun spiders respond to predators with aggressive displays, brandishing their pincers, biting or using their speed to escape.

When preparing to breed, male and female sun spiders engage in a mating "dance." Male sun spiders then flip the females onto their backs -- the males use their chelicerae to insert sperm into the females receptacles -- termed gonophores. After a lengthy gestation, the female digs a burrow in which she deposits as many as 200 eggs. Differing from scorpions and some other arachnids, which provide some parental care, most sun spider species provide no parental care.