Ceiestine Casto, age 11, of Wichita, Kansas, for her question:
How can a chameleon change color?
The frisky little anoles that live in our Southwest can change the color of their skins. This is why we often call them chameleons. However, zoologists insist that the genuine chameleon is a weird looking fellow, native to Africa and other warm countries of the Old World. This true chameleon is a champion turncoat. But even the champ cannot change his skin to match every color in the rainbow.
When a chameleon reposes in a dark room, his skin becomes yellow. He may wear the same shade of yellow when squatting on a white handkerchief outdoors in bright sunlight. When removed to a brown log, also outdoors in the sunshine, his yellow color may change to dark grey. Hence, this talented turncoat does not always match his surroundings. Besides this, red, purples and many other hues are beyond his range.
He can, however, turn many shades of green and yellow, plus a wide range of tones from pale grey to almost black. The secret of his astonishing talent lies within his skin and his color range is limited because his built in equipment is limited. When magnified under a microscope, the top layer of his skin resembles a mass of clear jelly, stuffed with marbles of assorted sizes and colors.
Looking down from the top, we see these miniature marbles are more or less sorted and arranged in three layers. Most of those in the top layer are yellow, the bottom layer is white and a layer of black pigmented cells is sandwiched in the middle. The chameleon is not limited to these colors because the pigmented cells can mirror outside colors and also blend two colors to create a third one.
The color scheme is governed by light, which strikes the chameleon's bulging eye and triggers responses in a special brain center. When he sits among sunlit foliage, the lower layer of white cells mirrors the blue sky. The blue rays reflect upward and blend with the surface yellow cells to create green. The chameleon then wears a green coat that more or less matches his green background.
Light reflected from a dark surface tends to trigger the black cells into action. When the chameleon is placed on a dark table top, the dark cells tend to grow and spread. They mask the white cells below and hide their blue sky reflection. As the dark cells expand, they spread fingers that mask the surface yellow cells. While these light sensitive activities are in progress, the chameleon changes from grey to darker and still darker grey.
Our little anole and the true chameleon are both lizards. The anole's natural skin color is green, speckled with dark pigmented cells. These cells may respond to light, temperature and perhaps also to emotions. In very strong light, they expand and blend with the natural green skin to turn the anole brown. They also expand and cause the anole to turn brown when he feels cold. Under normal conditions, the dark pigmented cells shrink and the anole wears his natural green color.