How do chameleons change color?
Chameleons change color by adjusting tiny crystals in special skin cells. Changing the spacing of the crystals alters how light is reflected, shifting their color.
Scientists once thought chameleons changed color by spreading pigments around, like octopuses. A 2015 study found that chameleons have a layer of skin cells called iridophores containing tiny guanine nanocrystals. When a chameleon is calm, the crystals are packed closely and reflect blue light, which mixes with yellow pigment to look green.
When the chameleon becomes excited, the crystals move farther apart, reflecting longer wavelengths like yellow, orange and red. A deeper layer of crystals reflects infrared light, which may help keep chameleons cool. Pigment cells with yellow, red or dark melanin also add to the effect.
Why they do it
Many people think chameleons change color mainly to blend in, but their color changes are often about communication and body temperature. Males show bright colors to rivals and potential mates, and dark colors absorb more heat on cool mornings. Stress, light and temperature all affect their color.
Did You Know?
Chameleons have tongues that can shoot out more than twice their body length in a fraction of a second to catch insects.