Spiders belong to the phylum Arthropoda and the class Arachnida, respectively. Over 34,000 species are found in each of the 100 families. Every spider poses a threat. But just a few species have venom that is harmful to people. A spider's biting apparatus consists of two chelicerae and venom sacs, which are where the poison is stored. Frequently, the venom is a clear liquid with a little greasy feel. The spider bites by spinning two punctures into the victim's body with its sharp, fang-like fangs. Spider venom appears to have a complex chemical make-up and to have both neurotoxic and hemotoxic effects. Local symptoms such as a scorching, throbbing, and painful sensation, numbness, stiffness, and maybe a very minor swelling at the site of punctures are frequently present after a bite. Most of the time, this symptom only lasts a short while—a few minutes to a few hours. Some poisons contain hemotoxins, which cause necrosis and gangrene by destroying the cells in the area. Cytotoxic, hemotoxic, and neurotoxic are the three types of toxicity. Black widow spiders (Latrodectusmactans), brown spiders, and tarantulas are among the spider species that can severely poison humans (lycosa species). Neurotoxic venom is produced by black widow spiders.