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
Dilute Russell's viper venom time Dilute Russell's viper venom time Dilute Russell's viper venom time (dRVVT) is a laboratory test often used for detection of lupus anticoagulant (LA). This "in vitro" diagnostic test is based on the ability of the venom of the Russell's viper to induce thrombosis. The venom contains some substances (RVV-V and RVV-X) which directly activate factor V and factor X, which turns prothrombin into thrombin in the presence of phospholipid and calcium. In the dRVVT assay, low, rate-limiting concentrations of both Russell's viper venom and phospholipid are used to give a standard clotting time of 23 to 27 seconds. This makes