Cleaner fish can recognize themselves in mirrors and photos, study claims

Cleaner fish can recognize themselves in mirrors and photos, study claims
via Rickard Zerpe (CC BY 2.0)
Bryan Ke
February 7, 2023
A newly updated study has found that the blue streak cleaner wrasse, Labroides dimidiatus, may be capable of recognizing themselves in reflections and photos based on mental self-images.
Researchers from Osaka Metropolitan University in Japan and the University of Neuchâtel in Switzerland published the study in the peer-reviewed journal Proceedings of the National Academy of Sciences on Monday.
In the study, the group contended that while some animals show remarkable evidence of mirror self-recognition, “implications for self-awareness remain uncertain and controversial.”
During the experiment, the scientists discovered that all the fish gathered for the study showed signs of self-awareness when they failed to show aggression towards pictures of themselves and only attacked photos of other fish.
In another experiment, scientists placed a brown-colored mark on the throat of eight of the cleaner fish that had spent a week with a mirror in their environment and were later presented with their photo bearing the same brown mark.
Interestingly, six of the eight cleaner fish showed throat-scraping behavior after being presented with the photo, suggesting that the “response to a mark on the body is a self-directed behavior and not a response to a perceived familiar individual or driven by kinesthetic-visual matching.”
Kinesthetic-visual matching is a type of recognition behavior in which the subject recognizes itself through a reflection by moving its body.
Even more interesting, the cleaner fish did not show throat-scraping behavior when scientists showed them unmarked pictures of themselves or pictures of familiar faces with the same mark on their chins.
It is believed widely that the animals that have larger brains will be more intelligent than animals of the small brain,” said animal sociologist Masanori Kohda, further suggesting that it is time to revise that belief.
Kohda and the group of scientists also performed the same experiments in their previous studies published on Feb. 17, 2022, and Feb. 7, 2019.
Describing the report as an “incredible study,” Frans de Waal, a Dutch primatologist at Emory University in Atlanta, said he thought that the self-recognition capabilities of the cleaner fish were “remarkable.”
De Waal, who was not part of the study, also pointed out that the fish that failed the mirror test do not necessarily lack self-awareness.
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