How does a chameleon change colors?

by anonymous on August 18th, 2005

Some Chameleon species are able to change their body color, which has made them one of the most famous lizard families. Contrary to popular belief, this change of color is not only an adaptation to the surroundings but also an expression of the physical and physiological condition of the lizard. The skin color is changed under influence of mood, light and temperature. The skin color also plays an important part in communication and rivalry fights.

Chameleons have specialized cells that lie in two layers under the chameleon's transparent outer skin. The cells in the upper layer, which are called chromatophores, contain yellow and red pigments. Below these chromatophores is a another cell layer. Cells of this layer are called guanophores and they contain the colorless crystaline substance guanin. These guanophores reflect amongst others the blue part of incident light. If the upper layer of chromatophores is yellow, the reflected light becomes green (blue plus yellow). A layer of dark melanin containing melanophores is situated even deeper under these blue and white light reflecting guanophores.These melanophores influence the lightness of the reflected light. All these different pigment cells can relocate their pigments, thereby influencing the color of light which is reflected.

(en.wikipedia.org)