Wednesday, April 18, 2007

Movement And Mimicry Can Fool The Enemy

Many small and normally drab insects rely on camouflage for protection. But should a hungry predator crack their disguise, they employ another visual trick: they transform their appearance with a flick of their wings, suddenly exposing vividly coloured patterns that momentarily startle the hunter, so allowing them to escape.

In Peru's rain forest, the brown, female leaf katydid (a relative of grasshoppers and crickets) flashes on and off a dazzling array of white marks, known as eyespots, on her hind wings. These are guaranteed to confuse an inquisitive predator such as a bird or lizard.

One type of Malaysian weevil with long, stiff legs continues to baffle naturalists. There appears to be no reason for an insect living in a rain forest to need such limbs. It cannot be for the same reason as an African Kalahari beetle, a desert dweller that uses its legs to keep its body off the hot sand. Perhaps the weevil's spindly legs help it to mimic the movements of certain spider-like and foul-tasting harvestmen that are avoided by predators. By aping the harvestmen, the weevils increase their chances of survival.

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