Wednesday, January 09, 2008
Changing shape and living longer
Few animals have come closer to achieving invisibility than the Central American glass frog. Its body is transparent in some places and dappled green and black in others. When it sits still on a leaf, its outline is so indistinct that it looks more like a small blemish on the foliage than a living creature.
This camouflage is known as splash camouflage, which blurs the frog's outlines. Nothing declares an animal's presence, nor identifies it. more readily than shape, so the ability to apparently change this is an invaluable aid to staying alive.
The skin patterns of the grey tree frog are arranged in such a way that they appear to continue across the frog and onto the branches to which it clings. Even the suction discs on its long toes are splashed with colour, and darker bands run right across its back and limbs, so that they merge into one overall shape.
Some South American tree frogs are similarly camouflaged, but can enhance their disguise by pulling their limbs into their bodies to blur their shapes even more.