Biological bristles, also known as setae (5 letters), are thin, stiff hairs found on the bodies of many animals. They are used for sensing the environment, gripping surfaces, and providing protection. Setae are made of chitin, a tough, flexible material that is also found in the exoskeletons of insects. Setae are an important part of the biology of many species, and can be found on the legs of spiders, the antennae of insects, and the skin of some amphibians.