American biologists have made a remarkable discovery in the pigfish, which can change color, like a chameleon, depending on the environment in which it swims.

How does that fish know if it has adapted so well to its environment that enemies will not notice it? According to biologist Laurian Schweckert of the University of North Carolina, the fish use their skin to do this.

Light-sensitive proteins beneath the color-changing cells allow the fish to “take a picture of its skin from the inside out.” In a way, the cells can tell a fish what its skin looks like because they can’t bend over to look.

According to Schweckert, the pigfish’s skin doesn’t function exactly like an eye, but rather is “a sensory feedback mechanism that allows the fish to follow its skin as it changes colour.” Remarkably, this mechanism continues to function when the fish dies. Until then, it continues to adapt its coloration to its surroundings.

The pigfish, according to Schweckert, could be the first example of a vertebrate with specialized light-sensing cells located outside the central nervous system.

Schweckert and her colleagues are now conducting more research to better understand which skin cells detect light and how the fish perceive it. However, they are really excited about their discovery. Because how color-changing animals are able to determine their color has remained a mystery until now.

It is possible that the pigfish color-checking mechanism also applies to other fish and perhaps even to other animals.