How do chameleons change color?

The chameleon is famous for one extraordinary ability: it can change the color of its skin. This talent has fascinated people for centuries and inspired countless myths. A common belief is that chameleons change color to blend into whatever surface they sit on, but the real story is different and more interesting. Color change in chameleons is driven by a remarkable piece of natural engineering hidden inside their skin, and it serves purposes that go far beyond simple camouflage.

For a long time, scientists thought chameleons changed color by moving pigment around in their skin, the way some other animals do. But research revealed a more surprising mechanism. Chameleons have a special layer of skin cells called iridophores, and inside these cells are tiny structures called nanocrystals arranged in an organized lattice. The spacing of these nanocrystals determines which colors of light are reflected. When a chameleon relaxes or stretches its skin, the spacing of the lattice changes, which changes the color the skin reflects.

When the nanocrystal lattice is tightly packed, it reflects shorter wavelengths of light, producing cooler colors like blue and green. When the chameleon excites and stretches its skin, the lattice spreads out, and it reflects longer wavelengths, producing warmer colors like yellow, orange, and red. Chameleons also have other skin cells containing yellow and red pigments, which combine with the structural colors from the iridophores. Together, these layers allow a chameleon to display an impressive range of colors and shift between them surprisingly quickly.

Chameleons do not mainly change color to hide. Their color shifts are largely a form of communication and a response to their condition. An adult male may flash bright, bold colors to intimidate a rival or to attract a mate, while calmer colors signal a relaxed state. Color also helps with temperature regulation, since a darker chameleon absorbs more heat from the sun and a lighter one absorbs less. Camouflage does play some role, as a chameleon's resting colors often blend with leaves and branches, but the dramatic color changes people find so amazing are mostly about mood, signaling, and survival.

This article was written using information from Wikipedia.