How Chameleons Change Their Colors to Brilliant Hues: Tiny Crystals
Chameleons have the amazing ability to change their colors. Now, though, scientists have found out how they do it. It turns out that the chameleons "tune" a lattice of nanocrystals present in their skin.
Most chameleons are popular for their ability to change color, depending on their social interactions. While scientists have figured out the mechanisms responsible for a transformation toward a darker skin tone in the past, though, they have been unable to find out what causes the transition from a vivid color to another lively hue. Some species, such as the panther chameleon, can carry out these colors changes within just one or two minutes to court a female or face a competing male.
Chameleons have brown, red and yellow pigments; however, they also have structural colors, which are generated without pigments via a phenomenon called optical interference. These colors result from interactions between certain wavelengths and nanoscopic structures, such as tiny crystals, that are present in the skin of reptiles.
In order to find out how panther chameleons end up changes from one bright color to another, the scientists closely examined the lizard, using their expertise in evolutionary biology and quantum physics.
"We discovered that the animal changes its colors via the active tuning of a lattice of nanocrystals," said Jeremie Teyssier, one of the researchers, in a news release. "When the chameleon is calm, the latter are organized into a dense network and reflect the blue wavelengths. In contrast, when excited, it loosens its lattice of nanocrystals, which allows the reflection of other colors, such as yellows or reds."
The scientists also found a second, deeper layer of iridophores. These cells, which contain larger and less ordered crystals, reflect a decent amount of infrared wavelengths. This, in particular, is excellent protection against the sun.
The findings reveal a bit more about exactly how chameleons change their colors. This could be especially useful for creating materials in the future that mimic these properties.
The findings are published in the journal Nature Communications.
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