Scientists Demonstrate Self-Awareness In Fish
Researchers from the Graduate School of Science, Osaka City University, have provided evidence to suggest that fish have the capacity for MSR, a behavioral test to determine whether an animal possesses the ability of visual self-recognition. As Phys.Org explains, an animal's capacity for MSR is determined when they "touch or scrape a mark placed on their body in a location that can only be indirectly viewed in a mirror." From the report: Professor [Masanori Kohda] says, "Previously, using a brown marking on the throat area of [cleaner fish Labroides dimidiatus], we had shown three out of four cleaner fish to scrape their throats several times after swimming in front of a mirror, a number on par with similar studies done on other animals like elephants, dolphins, and magpies." However, one of the criticisms laid against this result was sample size and the need for repeated studies showing positive results. Teaming up with researchers from the Max Planck Institute of Animal Behavior in Germany and the University of Neuchatel in Switzerland, this study increased the sample size to 18 cleaner fish, with a 94% positive result of 17 of them demonstrating the same behavior from the previous study.[...]Prof. Kohda says, "Our previous study demonstrated MSR in L. dimidiatus; however, studies with other animals have shown that simply moving a mirror reignites aggressive behavior, suggesting the animal has only learned a spatial contingency, not MSR." To address this, the team transferred mirror-trained cleaner fish to a tank with a mirror on one side of the tank and then three days later to a tank with a mirror on the other side, and saw the fish show no aggression toward their mirror image in both tanks. Also, to ensure the L. dimidiatus that passed the mark test truly are recognizing themselves, they placed mirror-trained fish in adjacent tanks that were separated by transparent glass. After two to three days, when fish largely reduced their aggressive behavior towards each other, they were marked the standard way the following night. None of the fish scraped their throat during the 120 mins of exposure to each other the following morning. This new experiment was recently published in PLOS Biology.
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