Marcia Whitaker, age 13, of Vancouver, B.C., Canada, for her question:
Can a chameleon really change his color
The word for the chameleon is unbelievable. His skinny tongue is longer than his body, his hands and feet are like two pronged pincers. He carries his lengthy tail in a coil and his eyes are set in bulging turrets that can be turned to look in opposite directions. And yes, his bumpy skin can change color which may happen to match his mood or the scenery.
Most of the world's 80 or so chameleons live in Africa, in the forested greenery either north or south of the sandy Sahara. The midgets of the family are two inches long, the giants measure two feet. Though all of them look somewhat like visitors from alien planets, they are lizards of earth's reptile clan.
The average chameleon prefers life among the treetops, where his two pronged feet take him slowly, very slowly along the boughs. After a few moments, he rests from his slow motion progress to survey the scenery. He does this by swiveling his bulging, turreted eyes one this way, one that way. When he spots a bug, he concentrates his gaze and takes aim. In less than a second, he flicks out his extra long, thin tongue and stuffs the victim into his big mouth.
During a pleasant afternoon, his bumpy skin may blend with the greenish gold of the shadowy, sun speckled foliage. Then something may alter his color scheme, for his remarkable skin can change through a range of greens, yellows and greys. Often the changes are triggered by varia¬tions in light and background. Sometimes he changes to express his moods. For example, if another male chameleon dares to enter his treetop terri¬tory, he is likely to turn almost black with rage.
Scientists are not certain how his nervous system controls his color changes. But they do know what happens inside his skin. Under the micro¬scope, a cross section of his skin looks like clear jello set with layers of tiny colored bodies and reflectors. Near the top, just below the clear surface layer, are yellow cells called xanthophores and red cells called erythrophores. At a deeper level are melanophores, cells colored with melanin like the pigment that adds freckles to human skins. Other layers reflect blue or white.
The chameleon can change his entire color scheme because these, or those color cells can swell up or shrink. When the brownies shrink, the yellows may blend with the blue reflectors to color the chameleon green. When the brown cells swell, they dim the other colors with grey. The brown cells' also can twine spreading fingers up through the skin, masking the other color cells. This happens when the usually peaceable chameleon becomes angry.
The true chameleons are not the only animals that can change the color of their skins. The leggy octopus changes through a range of pinks and pearly greys, usually to match his moods. In our southwestern deserts lives a pretty little lizard called the anole. Some people call him a chameleon because he can change through a range of greens and browns. Usually he wears brown in the shade and green in the sunshine.