Jacqueline de Jong, age 11 of Lethbridge, Alberta, Canada, for her question:
How does a chameleon change his color?
Though he looks somewhat like an escapee from an impossible flying saucer, the chameleon is a genuine earthling. Actually he is an Old World lizard with some very odd features. His bulging bug eyes roll around, usually in opposite directions, while he clings to the branches with clawed toes and a long, grasping tail. His less¬than beautiful body looks as if somebody had squeezed it between a couple of books. When not in use, his prehensile tail rolls itself into a flat coil.
Most people think that the weird looking little chameleon changes color to blend in with his background. This may or may not be true. Certainly on a sunny day he wears green that more or less matches the surrounding leaves. In the dark he tends to become nearly invisible by changing his outfit to dark grey or almost black. But this remarkable turncoat cannot change his color to red or match himself to a purple background. Obviously his color changes are limited.
His magical maneuvers take place down inside his thick lizard skin. Imagine if you can a clear jellified substance populated with assorted marbles of yellow, black and white. If all the yellows, say crowd to the top they hide the other two colors. The surface appears yellow. On a minature scale, plus a few extra tricks, this is what happens inside the chameleon' s skin. His roving eyes are sensitive to certain wavelengths of light and their signals cause changes in some of the mini marbles in his skin. Other tiny color bodies reflect colors from his surroundings.
The top layer of tiny color bodies is mostly yellows. Whites are at the bottom and blacks are sandwiched between. On a clear, cloudless day, the bottom layer of whites mirror the sky. The blue reflects up and blends with the yellows at the top. The blue yellow blend gives the chameleon a green skin.
If he happens to be clutched to a green leafy bough, then his color does indeed blend with his surroundings. But a cloudless day may trigger a similar skin reaction, even if the chameleon happens to be lolling in a bed of red roses. In that case, his green skin would contrast with his rosy background.
Strange changes occur when the chameleon finds himself on a dark surface, such as a black table. The black bodies expand, blotting out the whites below and their reflections. The black yellow blend turns the skin murky brown. As the blacks continue to expand they send inky fingers around and among the yellows. The chameleon turns almost black even if the rest of the room is done in rainbow colors.
In the Old World, there are 100 or so chameleons that have th;.s elaborate color changing mechanism. In the New World we call our anole a chameleon because he also changes color, somewhat. The natural color of our pretty little lizard's skin is green speckled with black color bodies. Usually he wears green. But when the black bodies enlarge, they blend with his basic green and his skin turns brown which may or may not match the scenery.