Scientists have demonstrated that fish think ‘it’s me’ when they see themselves in a picture. The researchers found that the determining factor was not the fish seeing their own body but seeing their face.
'It's me!' Fish Can Recognize Themselves In Photographs
Researchers from Osaka Metropolitan University have discovered that fish can recognize themselves in photographs, indicating an internal sense of self.
The study was conducted with the Labroides dimidiatus, commonly known as cleaner wrasse, who can recognize themselves in mirrors and attack other unfamiliar cleaner wrasse who intrude on their territory.
The researchers found that the determining factor for the cleaner wrasse to recognize themselves in a photograph was not seeing their own body but their face. The study included presenting each cleaner fish with four photographs:
- A photo of themselves
- A photo of an unfamiliar cleaner
- A photo of their own face on an unfamiliar cleaner’s body
- A photo of an unfamiliar cleaner’s face on their own body
The results showed that the cleaner wrasse attacked images with unfamiliar cleaner wrasse faces but did not attack photos with their own face.
Next, researchers conducted a mark test to confirm that the fish recognized themselves in the photos. They placed a mark on their throat in a photograph to mimic a parasite attached to them. Out of eight individuals tested, six that saw the photograph of themselves with the parasite mark tried to rub their throats against objects to clean it off. However, showing those same wrasse pictures of themselves without parasite marks or of a familiar cleaner wrasse with parasite marks did not cause them to rub their throats.
These findings suggest that the cleaner wrasse is not too dissimilar from humans in the way that it determines who is in a photograph. The fish looks at the face in the photo and makes a judgment about who that is, just like we do.
The researchers believe that this study is the first to demonstrate that fish have an internal sense of self-awareness, and the finding suggests that nearly all social vertebrates also have this higher sense of self.
Animal behaviorist Jonathan Balcombe, author of the book What a Fish Knows, is already convinced, describing the new study as “robust and quite brilliant.” People shouldn’t be surprised that fish could be self-aware given that they have already been shown to have complex behavior, including tool use, planning, and collaboration, Balcombe says. “It’s time we stopped thinking of fishes as somehow lesser members of the vertebrate pantheon.”
About the Labroides Dimidiatus
Labroides Dimidiatus, commonly known as the Bluestreak Cleaner Wrasse, is a unique fish that has the ability to form symbiotic relationships with other species.
These fish work together to create what is known as a “cleaning station.” Here, the Cleaner Wrasses remove any unwanted parasites that may have attached themselves to their fellow fish. They do this by performing a calming up and down movement of their tails, which invites other fish to their station. Once there, the Cleaner Wrasses may even clean the inside of larger fish’s mouths and gills.
The African and Maldivian Bluestreak Cleaner Wrasse is a beautiful fish that adds a lot of life to your saltwater aquarium. However, they are not a beginner fish. We recommend that only experienced marine aquarists consider this species. They require plenty of swimming room and should be housed with other fish of different shapes and colors. A tight-fitting lid or canopy is necessary because they can jump out of open aquariums or into uncovered overflow boxes.
The Bluestreak Cleaner Wrasse is a finicky eater and needs to be fed in small quantities of fresh, meaty food multiple times per day. Ideal offerings include small pieces of enriched frozen mysis shrimp, enriched frozen brine shrimp, and other smaller, meaty foods. Once fully adjusted to the home aquarium, these fishes can also be offered a high-quality marine flake and tiny marine pellet food to complement their staple diet of enriched frozen food.
The study has been published in the Proceedings of the National Academy of Sciences.
Story Source: Science Daily ‘It’s me!’ Fish recognizes itself in photographs, say scientists. A big step forward in vertebrate cognitive function research.
Materials provided by Osaka Metropolitan University. Note: Content may be edited for style and length.
M. Kohda et al. Cleaner fish recognize self in a mirror via self-face recognition like humans. Proceedings of the National Academy of Sciences. Published online February 6, 2023. doi: 10.1073/pnas.2208420120.
M. Kohda et al. Further evidence for the capacity of mirror self-recognition in cleaner fish and the significance of ecologically relevant marks. PLOS Biology. Published online February 17, 2022. doi: 10.1371/journal.pbio.3001529.
M. Kohda et al. If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals? PLOS Biology. Published online February 7, 2019. doi: 10.1371/journal.pbio.3000021.