Blending seamlessly into one's surroundings is known as being "chameleon-like" for a good reason — chameleons shift the colors and patterns of their skin to hide from predators in plain sight, or to communicate during social interactions with other chameleons.
But there's a secret, illuminated layer to chameleons' colorful signaling: Scientists recently discovered that the lizards' bones, particularly on their heads and faces, fluoresce through their skin, creating glow-in-the-dark patterns.
"Chameleons are already famed for their exceptional eyes and visual communication, and now they are among the first known terrestrial squamates [scaled reptiles] that display and likely use fluorescence," the scientists wrote in the study.
Biologists have long known that bones glow under ultraviolet (UV) light, but the researchers were astonished to learn that chameleons could harness this characteristic to display visible fluorescent patterns through their skin, study co-author Frank Glaw, a herpetology curator at the Bavarian State Collection of Zoology (ZSM) in Munich, Germany, said in a statement.
"That animals use this phenomenon to fluoresce themselves has surprised us and was previously completely unknown," Glaw said.
https://www.livescience.com/61454-chameleons-bones-glow.html