Scientists have found the mechanism used by chameleons to rapidly make complex colour changes, rendering them almost invisible.
The researchers at the University of Geneva say the changes take place via the active tuning of a lattice of nanocrystals in a layer of skin cells called iridophores.
The study, published in the journal Nature Communications, says the organisation of iridophores into two layers constitutes an evolutionary novelty.
It allows the chameleons to rapidly shift between efficient camouflage and spectacular display, while providing passive thermal protection.
Male chameleons are popular for their ability to change colourful adornments depending on their behaviour.
Some species, such as the panther chameleon, are able to carry out a change within one or two minutes to court a female or face a competing male.
“We discovered that the animal changes its colours via the active tuning of a lattice of nanocrystals,” the researchers say. “When the chameleon is calm, the latter are organised 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 colours, such as yellows or reds.”
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