Fishes can recognize their own face in pictures – just like humans, a new study reveals.
It shows they have an internal sense of self – adding to evidence they are far more intelligent than previously thought. Dubbed the “dunces of the animal kingdom,” they are said to have a memory span lasting three seconds.
Now a study has demonstrated they think “it’s me” when they see themselves in a photograph. The determining factor was not seeing their own body – but their face.
It is the first time the skill has been identified in creatures other than humans. But it could apply to other social vertebrates – ranging from lions and killer whales to naked mole rats.
Lead author Professor Masanori Kohda, of Osaka Metropolitan University, said: “This study is the first to demonstrate fish have an internal sense of self.”
The breakthrough has implications for a range of cognitive impairments caused by stroke, ADHD – or even Alzheimer’s.
In a series of experiments cleaner fish were presented with four snaps – of themselves, an unfamiliar individual, their own face on another’s body or vice versa. The species, known scientifically as Labroides dimidiatus, are known to recognize themselves in mirrors and fight off peers who intrude on their territory.
Interestingly, they only attacked those with the faces of unfamiliar cleaner fish. The results indicate the fish determined who was in the photograph based – in a similar way to us.
The Japanese team even ruled out the possibility they considered photographs of themselves as very close companions. Fish was presented with a photograph where a parasite-like mark was placed on their throat.
Six of the eight individuals that saw the photograph of themselves with a parasite mark were observed to rub their throats to clean it off. But showing those same fish pictures of themselves without parasite marks or of a familiar cleaner fish with parasite marks did not cause them to rub their throats.
Kohda said: “Since the target animal is a fish, this finding suggests that nearly all social vertebrates also have this higher sense of self.”
Evidence is growing their reputation for stupidity is greatly exaggerated. Last year German scientists showed fish can do complex sums. In experiments, they added and subtracted – from one to five.
Numerical skills were on a par with other invertebrate and vertebrate species. Experts are beginning to suspect they are as intelligent as birds and mammals. Counting is vital in daily activities of many species in the animal kingdom – boosting foraging, predator avoidance, schooling and mate choice.
It has been demonstrated in gorillas, monkeys, lemurs, dolphins, elephants, birds, salamanders – and even bees and spiders. Greater insight into their mental sophistication could pave the way for medical advances – assisting stroke patients or those with attention deficit disorders.
Zebrafish, for instance, carry 70 percent of the same genes as us – and 84 percent of those associated with human diseases.
The study was published in Proceedings of the National Academy of Sciences.
Produced in association with SWNS Talker.
