Chameleons have the ability to adjust layers of special cells underneath their skin to rapidly change colors, according to a group of scientists headed by Michel Milinkovitch, professor of genetics and evolution at the University of Geneva in Switzerland.
Chameleon skin cells are structured in layers that change depending on how light bounces off from the skin, scientists found. Unlike squid and octopus that emit colorants when provoked, chameleons rely on the structure of their skin to change into a variety of colors.
The study is titled Photonic Crystals Cause Active Color Change in Chameleons and was published in Nature Communications on March 10.
Researchers have found that the skin of chameleons has two thick layers of cells called the iridophore, which are shimmering in nature and have the ability to reflect light. The cells also contain nanocrystals that come in different sizes, shapes and structures. The chameleons have the ability to adjust the layers of iridophore cells either by relaxation or excitement.
“When the skin is in the relaxed state, the nanocrystals in the iridophore cells are very close to each other – hence, the cells specifically reflect short wavelengths, such as blue,” Milinkovitch told Live Science.
When the skin of a chameleon gets excited, the nanocrystals reflect longer wavelengths such as yellow, orange or red, blending with the animal’s naturally yellow pigmented skin, Milikonvitch said. The yellow color allows them to camouflage among trees and plants. On the other hand, the “red skin hue does not change dramatically during excitation, but its brightness increases.”
In order to conduct the study, Milinkovitch and his group of scientists investigate a type of chameleon found in Madagascar. They observed four adult female, five adult male and four juvenile Madagascar chameleons.