Venom types. Among the major classes of toxin in venoms are: Venom is widely distributed taxonomically, being found in both invertebrates and vertebrates; in aquatic and terrestrial animals; and among both predators and prey. The major groups of venomous animals are described below. Venomous arthropods include spiders, which use fangs — part of their chelicerae — to inject venom; and centipedes, which use forcipules — modified legs — to deliver venom; along with scorpions and stinging insects, which inject venom with a sting. In insects such as bees and wasps, the stinger is a modified egg-laying device — the ovipositor. In
Evolution of snake venom eggs, meaning that the snake had no use for its venom. This has led biologists to suggest that if venom is not used by a species, it is rapidly lost. Venom atrophication has also occurred following the evolution of constriction as a method of prey capture that does not require venom. Constriction is hypothesized to have evolved independently in several lineages. North American ‘rat snakes’ such as the Corn snake "Pantherophis guttatus" use constriction to trap and kill their rodent prey, and do not possess functional venom. A similar process has occurred in the African colubrid lineage Lamprophiidae, such as