Researchers Discover What Makes Chameleons Change Colors

Chameleons rapidly change color by adjusting a layer of special cells nestled within their skin, according to a new study.

Unlike other animals that change color, such as the squid and octopus, chameleons do not modify their hues by accumulating or dispersing pigments within their skin cells, researchers report in the journal Nature Communications.

This explains how the reptile can rapidly change color and appearance. Depending on the position of the chameleon's skin, the crystals reflect different levels of light that enable it to shift colors.

When the chameleons get excited or scared, the lattice stretches, letting the iridophores reflect different wavelengths of light.

"They are like selective mirrors," Michel Milinkovitch a co-author of the study told the BBC. "Light will bounce on them only for specific wavelengths. ... The other wavelengths will not bounce on these cells."

The paper shows that larger crystals organized in deeper populations of iridophores on chameleons reflect more substantial amounts of sunlight. This sunlight is reflected especially in the near-infrared range.

The researchers also found a layer of skin even deeper inside the chameleon's skin that seems to reflect near-infrared light. They think that this might be how chameleons manage to keep cool in hot climates.