STANFORD, Calif., May 20 (UPI) — U.S. biologists say fish looking at themselves in a mirror become feisty but fearful, suggesting more brain activity than had been suspected.
Stanford University Professor Russell Fernald, postdoctoral researcher Julie Desjardins and colleagues said the behavior suggests the fish are encountering something so far outside their realm of experience, it results in an emotional response.
The scientists compared the behavior and brain activity of male African cichlids during and after one-on-one encounters with either a mirror or other another male of about the same size.
Territorial male cichlids usually react to another male by trying to fight with it in a sort of tit-for-tat manner. Desjardins suspects the fish fighting their own reflections become fearful because the enemy in the mirror doesn’t exhibit the reactions they expect from another fish.
“In normal fights, they bite at each other, one after the other … but it is always slightly off or even alternating in timing,” Desjardins said. “But when you are fighting with a mirror, your opponent is perfectly in time. So the subject fish really is not seeing any sort of reciprocal response from their opponent.”
The discovery that fish can discern a difference so subtle “opens the door for us to better understand what is going on in the brain of non-mammalian animals,” Desjardins said.
The study is to appear in the journal Biology Letters.
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