Snakes get toxins from toad snacks

Giving credence to the adage, "you are what you eat," scientists have discovered that the Asian snake Rhabdophis tigrinus acquires its defensive poison by munching on toxic toads (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.0610785104). To protect themselves from predators, Bufonidae toads secrete cardiotonic steroids, known as bufadienolides, onto their skin. The toxins aren't sufficient to thwart a hungry R. tigrinus, however. After feasting on a toady treat, the snakes store the poison in glands in a ridge on the back of their necks (shown). The steroid backpack then provides the R. tigrinus, which lacks a venomous bite, with a unique chemical defense mechanism. The snakes will sometimes taunt predators into taking a poisonous taste, according to herpetologist Deborah A. Hutchinson of Old Dominion University, Norfolk, Va., chemist Jerrold Meinwald of Cornell University, and their coworkers. In contrast, R. tigrinus snakes living on an island free of the toxic toads possess no poison and are more likely to flee when confronted by a predator.