Cleaner wrasse check their body size before fights due to having their own mental representation.
Researchers at Osaka Metropolitan University discovered that bluestreak cleaner wrasse use mirrors to assess their size relative to potential competitors, marking the first evidence of private self-awareness in non-human animals. This behavior supports the theory that these fish possess mental states like body image and goals, suggesting a complex level of self-awareness previously unrecognized in fish.
Fish and Self-Awareness
What if that proverbial man in the mirror was a fish? Would it change its ways? According to an Osaka Metropolitan University-led research group, yes, it would.
Today (September 11) in Scientific Reports, researchers report that for the first time, a non-human animal has demonstrated possessions of some mental states (e.g., mental body image, standards, intentions, goals) which are elements of private self-awareness. According to the study, bluestreak cleaner wrasse (Labroides dimidiatus) checked their body size in a mirror before choosing whether to attack fish that were slightly larger or smaller than themselves.
The team of OMU Graduate School of Science student Taiga Kobayashi, Specially Appointed Professor Masanori Kohda, Professor Satoshi Awata, and Specially Appointed Researcher Shumpei Sogawa, and Professor Redouan Bshary of Switzerland’s University of Neuchâtel, were among the group that last year reported the cleaner wrasse could identify photographs of itself as itself, based on its face through mirror self-recognition.
Insights Into Evolution of Self-Awareness
This time, the cleaner wrasse’s behavior of going to look in the mirror installed in a tank when necessary indicated the possibility that the fish were using the mirror to check their own body size against that of other fish and predict the outcome of fights.
“The results that fish can use the mirror as a tool can help clarify the similarities between human and non-human animal self-awareness and provide important clues to elucidate how self-awareness has evolved,” doctoral candidate Kobayashi declared.
Reference: “Cleaner fish with mirror self-recognition capacity precisely realize their body size based on their mental image” by Taiga Kobayashi, Masanori Kohda, Satoshi Awata, Redouan Bshary and Shumpei Sogawa, 11 September 2024, Scientific Reports.
DOI: 10.1038/s41598-024-70138-7
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