Cleaner wrasse show self awareness in stunning mirror experiments
Science Daily
February 23, 2026
AI-Generated Deep Dive Summary
Cleaner wrasse have demonstrated a surprising level of self-awareness in groundbreaking experiments involving mirrors. Scientists at Osaka Metropolitan University discovered that these fish not only recognize their reflections but also engage in complex behaviors previously thought to be exclusive to mammals like dolphins. When marked with fake parasites, the wrasse quickly learned to use the mirror to locate and remove the markings, a response that was far faster than observed in previous studies. Even more remarkable, some fish picked up small shrimp, carried them to the mirror, and released them to watch how their reflections moved—a behavior described as "contingency testing." This deliberate exploration suggests a sophisticated understanding of their environment and their own bodies.
The experiments were conducted by placing marked wrasse in tanks with mirrors. The fish initially reacted to the marks on their bodies but couldn’t see them without a mirror. When the mirror was introduced, they quickly began scraping at the markings, often within the first hour. This rapid response surprised researchers, who had previously observed similar behaviors taking days to develop. The study’s lead author, Dr. Shumpei Sogawa, explained that reversing the order of introducing the mark and the mirror likely triggered this faster reaction, as the fish were already aware of something unusual on their bodies.
The shrimp behavior was even more unexpected. After several days of exposure to the mirror, some wrasse picked up tiny pieces of shrimp from the tank floor and intentionally dropped them near the mirror. As the shrimp drifted downward, the fish tracked its movement in the reflection, touching the glass repeatedly while observing the mirrored image. This action resembles behaviors seen in manta rays and dolphins, which release bubbles to study their reflections. The researchers described this as a form of exploratory “contingency testing,” where the fish used an external object to investigate how the mirror worked.
These findings challenge long-held assumptions about self-awareness being limited to a select group of animals. While cleaner wrasse have previously shown the ability to recognize themselves in photographs, this study suggests they may possess even greater cognitive abilities. The behavior observed—using mirrors for both practical purposes and exploratory testing—indicates flexible, self-related processing rather than simple conditioning or confusion.
The implications of this research are significant for understanding animal intelligence and the evolution of self-awareness. It raises the possibility that such capabilities may be more widespread across diverse species, including those beyond mammals. As Dr. Sogawa noted, this could expand our understanding of mirror self-recognition to include a broader range of animals, particularly those known for tool use. The study also highlights the importance of exploring self-awareness in a wider variety of creatures, including invertebrates.
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Originally published on Science Daily on 2/23/2026