Cichlids recognise faces
The Masked julie, Julidochromis transcriptus, from Lake Tanganyika, has the ability to recognise individual faces, making them more relaxed around familiar fish and more guarded with strangers. It identifies other fish using the pattern around the eyes, researchers have discovered.
In the wild, J. transcriptus lives in rock crevices hidden by vegetation, so only a small part of its body tends to be visible at any time.
Scientists placed eight adult males from a group of familiar individuals in an aquarium, then exposed them to digital models of fish with both familiar and unfamiliar features on both their heads and bodies. They found the males spent more time following those models whose faces they did not recognise, in order to monitor any potential threat.
“We found that our subjects were especially guarded against only unfamiliar face models, regardless of body type,” says Takashi Hotta of Osaka City University in Japan.