Albert Sivley, aged 12, of Houston, Texas for his question:

How does a lizard change his color?

Certain lizards can change the color of their coats. Among them are the chameleons and the false chameleons. There is nothing false about the false chameleon except that he is not closely related to the true chameleon. The little fellow can change his color, though he has not such a wide range of colors as the true chameleon. The false chameleon is more properly called the anble. The anble is a delightful pet to own.\You need a microscope to see what these fellows use to change color.  A section of skin, highly magnified, shows where the different colors are carried.  The colors, or pigments, look like tiny beads set in a mass of light jelly. The colored beads tend to arrange themselves in layers. _

Let's examine the skin of the true chameleon, since he has the biggest color wardrobe. Near the top, just under the surface of the skin, is a layer of minute yellow beads. Below them is a layer of tiny black beads. And there is a layer of pale, whitish beads at the bottom, The chameleon uses only these three colors to clothe himself in yellow, grey, green, tan, brown and almost black.

The trick is done with mirrors. For the layer of whitish beads reflects light upward from below. Often they reflect light as blue. When this happens, the blue tone shines through the yellow beads. This, of course, comes out as green: We see a green lizard.

Also present in the lizard’s skin are nerve cells, Nerve cells are also present in his swivel‑saucer eyes. These nerve cells carry information about lighting conditions to the brain. The brain sends back orders for action. When light reflected from a dark color falls on these nerve cells they send orders to the layer of black beads. The black beads begin to swell. They extend fingers and fringes through the yellow beads. They block out the white reflector beads below. The changeable lizard fades to tan and deepens to almost black,

When no light reaches the skin, the black beads shrink again. No blue light is reflected from the white beads either. So, in a dark room, a chameleon becomes yellow. Various lighting effects produce his changing wardrobe. On a dark background and a strong light, he wears grey. On a white background in a strong light, he becomes yellow ‑ the same color he wears in the dark.

The little anole uses the same system to change his wardrobe. however, he keeps to colors of green and brown. He tends to wear green in bright sunlight and brown in the shade. None of these lizards dress to match their background, though they sometimes happen to do so.