The tiny fish showed signs of surprising levels of intelligence in a mirror test experiment, allowing them to not only recognize themselves in their reflections, but also use food to investigate how mirrors work.

mirror mark test A standard scientific experiment used to investigate self-awareness in animals and measure how similar the intelligence of other species is. to our own.

Looking at your reflection and fixing smudged eyeliner is a telltale sign. Self-awareness. YSince we know that dirt on the face is out of place, we can use reflection as a proxy to pinpoint where to wipe the dirt.

Theoretically, reactions to out-of-place marks in reflections are thought to be evidence of self-recognition in other animals as well. chimpanzee, elephantand dolphin They are only a few who pass this mark test, and many consider it a sign of intelligence similar to ours.

Cleaner Bella (Labrodes dimidiatus) is a finger-sized saltwater fish that gets its name from eating the parasites and dead tissue of other larger fish. that first reported To pass the 2018 mirror test.

It’s not hard to see why Cleaner Bella is a good candidate. Their modus operandi is to clean the fish, so perhaps any parasite-like marks on their bodies will force them to use a mirror to “refresh” themselves as well.

Although this is a 2018 survey, reported Evolutionary psychologist Gordon Gallup, the creator of the mirror mark test, said the fish passed the test. said new scientist he believed The fish in these experiments mistook traces on their bodies for parasites on other fish.

Now, a team from Osaka Metropolitan University in Japan and the University of Neuchâtel in Switzerland has tweaked the experiment to further examine Bella’s self-awareness.

“In previous mirror studies of cleaner wrasse, the typical procedure was for the fish to look at the mirror for a few days, get used to it, stop making social responses, and then marks were added,” said Shunpei Togawa, an animal behaviorist at Osaka City University. explain.

“In this study, the order was reversed: the fish were marked first, and then the mirror was introduced for the first time. The fish may have been aware that something was wrong with their body, but they couldn’t see it. When the mirror appeared, it immediately provided visual information that matched existing body expectations, so scraping happened much faster.”

Although far from perfect control, it goes some way to improving initial experimental designs, giving fish time to identify “parasites” in their bodies before they encounter reflexes.

Scientists were surprised at how quickly the fish responded in these new experiments. On average, they tried to scrub off the “parasites” within about 82 minutes. They say this means self-awareness before being exposed to the mirror.

After the fish spent several days getting used to the mirror, scientists noticed that the fish was behaving abnormally. They picked up a small shrimp from the bottom of the tank, carried it to the mirror and dropped it.

When the mirror shrimp fell in sync with the real thing, the fish carefully followed its reflection while touching the mirror surface with their mouths.

Togawa and his team believe this is how fish explore the properties of mirrors, using objects that are different from themselves to better understand how reflected images work.

This type of “accidental testing” and use of mirror tools has also been observed in several other species that have failed mark-based mirror tests. pig, rhesus monkey, manta rayand Crow.

Related: Cephalopod passes cognitive test designed for human children

“The results of this research may have direct implications not only for academic issues such as revising the theory of evolution and constructing self-concept, but also for issues related to our lives, such as animal welfare, medical research, and even AI research.” say Biologist Masanori Koda was involved in both this new study and the original paper on self-recognition in wrasse.

The researchers say these findings suggest self-awareness. once thought This ability is unique to great apes and may actually be present in a wider range of animals, including fish.

“Our findings suggest that self-recognition evolved minimally in teleost fishes (450 million years ago) and is likely widespread across vertebrates,” the researchers said. write.

This research scientific report.