Article by: Nur Hidayahanum Hamid

Source: Osaka Metropolitan University

A research team led by Professor Masanori Kohda from Osaka Metropolitan University discovered that fish can recognize themselves based on their face rather than their body. The study focused on Labroides dimidiatus, commonly known as cleaner fish, which can recognize themselves in mirrors. The fish were shown four photos: themselves, an unfamiliar cleaner fish, their face on another fish's body, and another fish's face on their body. The cleaner fish did not attack photos featuring their own faces but did attack those showing unfamiliar faces, indicating that they use facial recognition similar to humans.

To confirm self-recognition, a photo mark-test was conducted. Fish were shown a photo of themselves with a parasite-like mark on their throat. Six out of eight fish rubbed their throats in response, attempting to "clean" the mark, while they did not react to photos of themselves without the mark or of familiar fish with marks. This study is the first to show that fish have an internal sense of self, suggesting that many social vertebrates could possess this higher level of self-awareness. The findings were published in Proceedings of the National Academy of Sciences.

Picture 1: The Labroides dimidiatus, commonly known as a cleaner fish, can recognize “It’s me!” when they see themselves in a picture (Credit photo: Masanori Kohda, Osaka Metropolitan University).

Picture 2: A: Faces of study fish. B: The photographic models used in the experiment. SS: Complete image of self, UU: Complete image of unknown fish, SU: Self-face/unknown body, US: Unknown face/self-body (Credit photo: Masanori Kohda, Osaka Metropolitan University).

Date of Input: 11/09/2024 | Updated: 13/09/2024 | hidayahanum