Sept. 4, 2018 (Phys.org) -- An international team of researchers has found a small tropical fish that is capable of passing a classic test of self-awareness. The results are published on the bioRxiv prepress server.
Since the 1970s, a test developed by Gordon Gallup has been the gold standard for testing for self-awareness -- researchers make a mark on a creature's face and introduce a mirror. If the animal makes some attempt to touch or remove the mark, they are deemed to have self-awareness.
Since the test first came into use, only a few animals have ever passed the test. Besides humans, the list currently includes chimpanzees, bonobos, orangutans, dolphins, elephants and pigeons. Others have responded in ways that have left their results in dispute.
In this new effort, the researchers tested the relatively unknown cleaner wrassea -- tiny tropical fish. Prior research has shown that they have very good eyesight and go after parasites on the bodies of other fish. They are also very territorial.