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
Platypus venom characteristic uniquely, the platypus simply inherited its venom from its distant ancestors. Rather than being a unique outlier, the platypus is the last demonstration of what was once a common mammalian characteristic, and it can be used as a model for non-therian mammals and their venom delivery and properties. The venom is produced in the crural glands of the male, which are kidney-shaped alveolar glands located in the upper thigh connected by a thin-walled duct to a calcaneus spur, or calcar, on each hind limb. Female platypuses, in common with echidnas, have rudimentary spur buds that do not develop (dropping