Normally, having a fish spit in someone’s face would sound both absurd and disturbing. But for the scientists behind a new animal study, that was exactly what they’d hoped would happen. By training archerfish to spit on images of people, they were able to show for the first time that fish are capable of doing something extremely complex: recognizing human faces.
In the study, published today in Scientific Reports, researchers at the University of Oxford and the University of Queensland showed archerfish pairs of human faces, one of which was familiar to them. Then, the fish had to choose the right face to get a reward. Because archerfish have the ability to spit jets of water to knock down insects from branches (yes, really), figuring out which face the fish picked wasn't all that hard. All the researchers had to do was train fish to spit at the picture they choose.
When the pictures were presented to fish in color, they picked the face that was familiar to them 81 percent of the time, the researchers say. But when the fish were shown black-and-white images, they got even better: they picked the right face 86 percent of the time.
This isn't the first time that fish have demonstrated their ability to recognize animals based on their faces. Back in October, the same team announced that Ambon damselfish can recognize other fish belonging to their species thanks to their facial patterns, which are only visible to animals who can see ultraviolet wavelengths. And this ability extended to another species, the lemon damselfish. But today's study pushes things a lot further. It suggests that despite the archerfish's small and simple brain, it's still possible for an animal to perform complex and demanding visual tasks.
Also: Archerfish are really good at spitting at things.