Fish has Self-Recognition Capabilities, Says Study Using Photos

Fish have self-recognition via photos, as recorded for the first time in animals, according to a research team. The team, led by Professor Masanori Kohda from Osaka Metropolitan University's Graduate School of Science, found that the fish seeing their face rather than their body was the deciding factor.

By using their internal representations of faces, humans can easily distinguish between images of familiar people, including themselves, and images of strangers. Self-face recognition allows humans to recognize their faces in mirror reflections.

Mirror Self-Recognition

Mirror self-recognition (MSR) is a skill that some animals possess, but its implications for self-awareness are still up for debate.

Researchers from the University of Florida demonstrated in their study that cleaner fish, scientifically known as Labroides dimidiatus, probably recognize their mirror image using a mental picture of the self-face similar to humans. By eating parasites and dead skin, cleaner fish keep fish tanks clean and act as housekeepers for the other fish species.

The researchers found that fish who had never seen a mirror attacked both pictures of themselves and pictures of strangers quite frequently.

After passing the mirror test, aggression remained against unfamiliar and composite photographs of stranger face/own body but decreased toward their photos and composite photos of their face/stranger body.

According to the study's findings, cleaner fish with MSR abilities can identify their mirror image by imagining their face instead of comparing their body movements in the mirror. This study shows that animals can recognize their own images.

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Cleaner Fish and Photos

Four photos were shown to each cleaner fish: one of themselves, one of a different cleaner fish, one of their face on the body of a different cleaner fish, and a fourth of the face of a different cleaner fish on their own body.

A peer-reviewed version of the study by Kohda and several colleagues was published in the Proceedings of the US National Academy of Sciences.

It's interesting to note that the cleaner fish attacked pictures of unfamiliar or unknown cleaner fish but not ones of themselves. These findings collectively suggest that cleaner fish, like people, identified the person in the picture based on the face but not the body.

A photograph mark test was carried out to rule out the possibility that the fish thought of photos of themselves as very close friends. Fish were shown a photograph of a throat mark that looked like a parasite. The researchers found that six out of eight people who saw a photo of themselves bearing a parasite mark rubbed their throats to remove it. The same fish did not rub their throats when photos of them without parasite marks or a well-known cleaner fish with parasite marks were shown to them, Science Daily reports.

Kohda said that this was the first study to show that fish have an innate sense of self. Given that fish are the target species, this finding implies that almost all social vertebrates also possess a stronger sense of self, The Jerusalem Post reports.