Spider

Spiders are rapacious invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. They are confidential in the order Araneae, one of several orders within the larger class of arachnids, a group which also contains scorpions, whip scorpions, mites, ticks, and opiliones (harvestmen). The study of spiders is known as araneology.

All spiders produce silk, a thin, strong protein filament extruded by the spider from spinnerets most normally found on the end of the abdomen. Many species use it to trap insects in webs, though there are also many species that hunt generously. Silk can be used to aid in climbing, form smooth walls for burrows, build egg sacs, wrap prey, and provisionally hold sperm, among other applications.

All spiders excluding those in the families Uloboridae and Holarchaeidae, and in the suborder Mesothelae (together about 350 species) can insert venom to protect themselves or to kill and dissolve prey. Only about 200 species, however, have bites that can pose health problems to humans. Many larger species' bites may be quite tender, but will not produce lasting health concerns.