neurotoxin

The nervous system is almost all-powerful in the body: all five senses depend on it, as do breathing, digestion, and the heart. So it's an obvious target for poisons, and neurotoxins have developed as weapons in many animals, including snakes, bees, and spiders. Some wasps use a neurotoxin to paralyze their prey so that it can be stored alive to be eaten later. Snake venom is often neurotoxic (as in cobras and coral snakes, for example), though it may instead be hemotoxic (as in rattlesnakes and coppermouths), operating on the circulatory system. Artificial neurotoxins, called nerve agents, have been developed by scientists as means of chemical warfare; luckily, few have ever been used.