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 splicing. The Elapid snake "Bungarus fasciatus", for example, possesses a gene that is alternatively spliced to yield both a venom component and a physiological protein. Further diversification may have occurred by gene loss of specific venom components. For instance, the rattlesnake ancestor is believed to have had genes for neurotoxic PLA2 toxins, which are absent in modern non-neurotoxic "Crotalus" species. The various recruitment events had resulted in snake venom evolving into a very complex mixture of proteins. The venom of rattlesnakes, for example, includes nearly 40 different proteins from different protein families, and other snake venoms have been found to