Humans have long been fascinated by chameleons changing colour to dazzle mates, scare rivals and confuse predators.
On Tuesday, scientists said they uncovered the mechanism of the feat, and that the results of their investigation astounded them.
Rather than use pigments to switch colour, nanocrystals in the lizards’ skin are tuned to alter the reflection of light, they found.
“We were surprised,” Michel Milinkovitch, a biologist at the University of Geneva told AFP.
“It was thought they were changing colour through… pigments. The real mechanism is totally different and involves a physical process,” he added.
Colour-switching in chameleons is the preserve of males.
They use it to make themselves more flamboyant to attract mates and frighten off challengers, or duller to evade predators.
The mature panther chameleon used in the study, for example, can change the background colour of its skin from green to yellow or orange, while blue patches turn whitish and then back again.