Chameleons change colour by shifting crystals around inside their skin cells

New theory fundamentally changes understanding of how chameleons’ bright colours are made

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The Independent Online

Chameleons rearrange crystals inside special skin cells to change their bright colours, new research has found.

The reptiles shift around the cells to change which wavelengths of light are reflected by their skin, Swiss researchers have found. They tune a complicated collection of tiny crystals that are in skin cells called iridophores to choose how they will appear.

As well as creating the bright and luminous colours often seen on chameleons, the cells also help the animals keep cool. A second layer of iridophores, beneath the ones that choose colour, have bigger crystals to reflect back infrared light.

The research completely changes the understanding of how chameleons change their colours. It was produced by physicists from the University of Geneva in Switzerland, and published in the journal Nature Communications.

Physicist Jeremie Teyssier, who worked on the study, said: "We discovered that the animal changes its colours via the active tuning of a lattice of nanocrystals.

"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."

Researchers found the results by studying the panther chameleon, from Madagascar. They found tah that the chameleon actively controls how the cells are arranged, and what colour it will be.