Snake "Steals" Toad Toxins for Defense Against Predators

January 30, 2007

Sometimes the best defense isn't a good offense—it's a good diet.

A new study shows that some snakes can store toxins from toads they eat and use the debilitating chemicals as a defense mechanism.

The toads make the toxins to protect themselves against predators, which learn not to eat the deadly amphibians.

But the Asian snake Rhabdophis tigrinus has evolved a way to cosume the toxic meal safely.

Instead, the snake stores the toad toxins in glands in its neck, making it too poisonous to eat.

These snakes even taunt enemies to attack, according to the new research, which appears in this week's issue of the journal Proceedings of the National Academy of Sciences.

The snakes also pass the toxins on to their offspring to protect them while they are too young to eat toads themselves.

Deadly Meal

Asian snakes are hunted by a number of predators, including hawks, salamanders, and other snakes. But the species responds with stylized movements that take advantage of its stored toxins.

"The snakes bend their head over and expose the glands on the back of their neck," said Deborah Hutchinson of Old Dominion University in Norfolk, Virginia, who worked on the study with colleagues in the U.S. and Japan.

"They also ... do neck-butting, where they actually move the neck toward the attacker."

The snakes are apparently goading predators into taking a swipe or a bite. (Related: "Snake Threat May Have Spurred Evolution of Primate Eyes" [August 10, 2006].)

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