10-12-10

Even though a male cichlid is one tough fish, he may be scared of his own reflection. A new study shows that squaring off to fight a mirror opponent can be worse than fighting a real foe. Male cichlid fish readily attack other males as well as mirror images of themselves, posturing and lunging with the same aggression, says Julie K. Desjardins of Stanford University. Yet the reflection-fighting males show heightened activity in a part of the brain associated with fear and other negative reactions in vertebrates, she and Stanford colleague Russell Fernald have found. Tangling with a real male doesn’t stir up that response, the researchers report in a //Biology Letters// study released online the week of May 11. Desjardins hesitates to equate whatever is going on in the fish brain with the human concept of “fear,” but she says the reaction to mirror images is indeed “negative.” Earlier studies of fish and mirrors have suggested that fish just mistake their reflections for some impertinent, other fish that needs a good trouncing. The new paper gives the first indication of differential brain activity when fish meet mirrors, Desjardins says. Scientists have a long tradition of studying animal reactions to mirrors as a way of trying to explore animal consciousness. Great apes, elephants, dolphins and magpies show evidence of recognizing themselves when gazing into mirrors, says Diana Reiss of Hunter College in New York City, who studies animal cognition. In experiments done so far, other animals, including monkeys and fish, don’t seem to get it.