Scientists have discovered new insight into how chameleons change color.
Quantum physicists and evolutionary biologists at the University of Geneva found that chameleons have tiny photonic crystals in their skin, allowing them to manipulate light and
rapidly change colors, the study published in the journal Nature said.
The male panther chameleon can change from blue-green to yellow-red-orange in minutes,
The Los Angeles Times reported. The color changing ability is useful for courting a mate, competing with another male, or hiding from predators.
“I assure you: In Madagascar, they are really difficult to spot,” study co-author Michel Milinkovitch said, according to the Times.
The method differs from that of other color-changing animals such as squid and octopus, which
adjust pigments within their skin cells, said Scientific American.
Chameleons change the arrangement of the crystals in their skin, and thus their color, by relaxing or exciting the skin.
"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 said, according to Scientific American.
Chameleons’ skin includes two layers of cells that contain different-sized crystals.
The two layers are a unique find, suggesting that one layer evolved to affect color change while the other serves to
reflect heat and keep the animal cool, the BBC reported.
"What is really novel about this study is that it shows that there are two layers of these iridophores, not just one. And the crystals in the deeper layer affect not just visible color but also how the skin reflects the near-infrared — a part of the spectrum of sunlight that neither we nor chameleons can see," Devi Stuart-Fox, an expert in animal colouration and senior lecturer at the University of Melbourne, told the BBC.