There are about 35,000 species of spider worldwide. They are characterized by four pairs of legs and an unsegmented furry or polished "abdomen". They all produce a poison in their fangs that acts as a neurotoxin. They also produce silk from their spinnerets though not all build webs. They are predators, catch their prey in various ways, immobilize it with their venom and then suck out the body fluids.