A Moment of Science

Snake Mimicry

Could you tell a coral snake from the similar looking, but non-poisonous scarlet king snake?

coral_snake

Photo: Zack Bittner

In Central America there are about twenty species of snakes that mimic the coral snake.

Could you tell a coral snake from the similar looking, but non-poisonous scarlet king snake?

You can look at the slight variations in pattern and see which one is poisonous. This type of coloring is classified as aposematic. A pattern is aposematic if it serves as a warning sign to the organism’s predators that they should stay away or else.

However, some patterns that look far out to us are actually camouflaging in a creature’s natural habitat. How can scientists be sure that a pattern is aposematic and not camouflaging?

In the wild in Costa Rica, the appearance of coral snakes was thought by some scientists to be camouflaging. An evolutionary biologist showed that the snake’s appearance was aposematic though by showing that birds were just as likely to avoid a coral snake if it were on a white paper background as when it was on a natural background. In Central America there are about twenty species of snakes that mimic the coral snake. This experiment also revealed that even the least impressive mimics were less likely to be attacked as a result of their aposematic mimicry of poisonous snakes.

How does a predator learn to avoid snakes of a certain pattern if the snake in question is deadly?

In this case, some birds have evolved an innate avoidance of the coral snake’s pattern. We know this because another biologist showed that birds raised in captivity are afraid of wooden dowels painted to resemble coral snakes.

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