To Keep Predators Away, Snake Pretends Its Rear Is a Head

By Allison Bond | August 6, 2009 6:36 pm

sea snakeScientists have discovered a clever way the yellow-lipped sea krait snakes deter predators: By making it look as though the venomous snake has two heads, according to a study published in the journal Marine Ecology.

A biologist first noticed the snakes’ tricky method while diving in Indonesia. Researcher Arne Rasmussen observed the animals foraging for food while simultaneously moving what appeared to be a bobbing head around–but that bobbing body part was really its tail. “[T]he tail was slowly writhing back and forth, much in the same way as the head moves on a vigilant and actively searching snake” [National Geographic News], said co-author Johan Elmberg, who did not see the snake, but teamed up for the study with Rasmussen.

This tail movement, combined with the darker pigmentation reminiscent of the snake’s real head, gives a predator the illusion that the snake is facing it with its venom-filled head, an important technique for the krait’s survival because the snakes are vulnerable to a number of predators, including larger fish, sharks and birds [BBC News]. Although the snake packs a potent venom, the animal becomes relatively defenseless while foraging, a time when its head is stuck in crevices of coral reefs rather than on the lookout for attacks [LiveScience].

After noticing the snake’s technique, scientists examined nearly 100 other sea krait species in museum collections, finding a similar distinctive color pattern in nearly 100 such species. The museum findings suggest other sea snakes might employ the guise observed [LiveScience]. Still, further investigation is necessary before scientists can say for sure that other sea snakes share the sneaky technique used by the yellow-lipped sea krait.

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Image: Arne Rassmussen

  • CW

    This is probably a dumb question, but I’ve always wondered something about poisonous snakes (and other animals). Do predators ever get sick or die after eating a poisonous snake? Or do predators know not to eat the parts of the snake that has the poison glands/sacks?

  • Gadfly

    In most instances the toxins are only deadly when in the bloodstream, hence the delivery method of a bite. Remember the old snakebite remedy of sucking out the poison? Inevitably some is swallowed without ill effect. Although the method is now discouraged because if you have undetected sores in your mouth you would absorb some of the toxins that way — probably not enough to kill in most cases but why take the chance. In any case, that’s why predators can eat venomous critters.


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