Kristine Hofstedt, age 12, of Milwaukee, Wis., for her question:
How many colors can a chameleon change to?
The pretty little anole of the New World is sometimes called a chameleon. He is a lizard who can change quite quickly between various shades of green and brown. Certain tree frogs also change color, but mire slowly. Neither of these charming turncoats is related to the true chameleon of the tropics.
This fellow is full of amazing tricks. He is a lizard from a few inches to two fact long ‑ depending upon his variety. He is a tree dweller, enemy of insects ‑ especially grasshoppers. His tail is prehensile ‑ or grasping ‑ and so are his hands and feet. His eyes are set in cone shaped bumps mounted like little turrets on his head. One can look this way, the other can look that way. Then searching for food, the two eyes scan the scenery by rolling around this way and that. They focus when the victim is sighted. In addition, the chameleon has a foot long tongue which darts in and out faster than a grasshoppar can hop.
Most remarkable of all is his ability to change color. No, he does not change to match his surroundings. And he cannot select any color in the rainbow. His colors are limited to various shades of green, yellow and grey. He does not turn groan because he happens to be sitting on a green leaf. Though he may turn green on a green leaf.
The secret of this turncoat is in his skin. Highly magnified, we see his skin as a layer of pale belly, spattered with tiny colored marbles. There are three layers of these colored round cells. The top layer is composed of yellow cells, the bottom layer is of white cells. In between is a layer of smaller black cells.
The white cells act as mirrors. Then the light is blue, these little mirrors reflect a blue tone up through the skin. The black cells are too small to notice. But the blue tone blends with the yellow cells at the surface ‑ and blue and yellow make green. On a sheet of blue blotting paper, our chameleon turns green.
The yellow and grey chameleon colors are produced by the yellow cells near the surface and the black cells in the middle of the sandwich. Those black cells are not always smalls inconspicuous dots. Under curtain conditions, they expand and grow. Their edge becomes fringes and little fingers spread up and even around the yellow cells. At such times, no light is reflected from the white cells below. Even the color from the yellow cells is dimmed, Our chameleon becomes a greyish colored follow.
The black cells are affected by light. There are light sensitive tolls in the animal’s skin and eyes. Light reflected from a dark object triggers the black cells and they grow. Sitting on a black blotter in bright sunlight, the chameleon turns grey.
In a dark room there is no 1ight to trigger the black cells, no light reflected from the white mirrors. The chameleon turns yellow. He is also yellow when sitting on a white blotter in bright sunshine. The light triggers the black cells to expand. But the order is canceled out by sensitive cells in the eyes. The dark cells remain small and the chameleon looks yellow.