Genes spiders use for venoms

Two of the best-known venomous animal groups on Earth are the snakes and spiders. Both produce venoms that comprise cocktails of different chemicals. Snakes do it by using an assemblage of genes that they've co-opted into venom production over evolutionary time. As a result, these genes produce venom proteins that tend to vary in the way they look and work. Spiders, on the other hand, appear to have done things differently: they've repeatedly used the same genetic template and varied it, as Kartik Sunegar explains to Chris Smith...