The Friends of Charles Darwin

Bluffing, the oldest trick in the poker-player's book, comes in rather handy in the natural world, too. The peacock butterfly, a perfectly tasty snack for a bird, often cheats death with what is nothing more than a bluff. Suddenly exposing the prominent eyespots on the butterfly's wings is enough to startle a foraging bird and save the insect's life, says Adrian Vallin, a zoologist at Stockholm University, Sweden.