Now scientists have identified a reptile that can see through its skin: the Moorish lizard.
Domenico Fulgione and a team of researchers publishing in the Journal of Zoology earlier this month noted that this species of lizard, Tarentola mauritanica, changed color after being placed on a dark surface, even when blindfolded.
Ed Yong, writing for Phenomena:
These bizarre results started to make more sense when the team analysed the gecko’s skin. They found that the skin is rife with opsins—light-sensitive proteins that are the basis of animal vision. When light enters your eyes, opsins in your retinas respond by triggering chemical reactions that send signals to your brain. That’s how you see. The Moorish gecko has plenty of opsins in its eyes too, but the team also found these proteins all over the skin of its torso. It’s especially common in the lizard’s flanks, and in cells called melanophores that are filled with dark pigments.
The researchers think that the flank opsins can respond to surrounding light levels and automatically adjust the gecko’s colour. If they’re right, the lizard has a kind of distributed vision that is independent of its eyes, and perhaps its brain. In other words, it can “see” with its skin.
Other talented color-shifters—like cuttlefish, tetras, and tilapias—have opsins on their skin, too, but this is the first example of a land-dwelling animal that uses them (presumably) to “see” its surroundings. Scientists still need to confirm that opsins are in fact detecting light and, in turn, sending signals to the rest of the body. The answer could hone our understanding of how the senses communicate with one another, as well as our ability to refine camouflage technologies that don’t rely on a single camera to survey a wearer’s environment.