Why do chameleons actually change color?

Chameleon color change depends on layers of skin cells called chromatophores and iridophores. By adjusting these cells, a chameleon can shift from darker to brighter or alter hue in response to mood, temperature, and social signals. A 2015 study on panther chameleons showed that rapid color change also involves microscopic crystal structures in the skin that change how light is reflected. Camouflage is part of the story, but communication is often more important. Many species use color shifts during courtship or territorial displays.