Changing hues

A chameleon’s skin has different kinds of cells. The uppermost layer of cells contains xanthophores, a yellow pigment. Eythrophores (red pigment) are mainly present in striped regions. Under this lies the iridophores that reflect different wavelengths of light. The final layer is melanophores, which have extensions that reach the skin’s top-most layer. When a chameleon is relaxed, the nanocrystals in the skin are closer to each other and reflect shorter wavelengths, like blue. When it is excited, the distance between nanocrystals increases and reflect longer wavelengths such as yellow, orange, or red. When it is time to hide, it turns to darker shades as the melanophores disperse pigments to the upper layers through their extensions.