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Fish Cannibals

February 14, 2007

For one fish species, cannibalism is the solution to a paternity question.


Eating away a paternity question. I’m Bob Hirshon and this is Science Update.

Cannibalism may sound like a drastic way out of a paternity dispute. But among male fish of the Indonesian species T. sarasinorum, it’s standard practice. According to Ph. D. student Suzanne Gray of Simon Fraser University in Canada, when a male of the species spawns, other males sometimes sneak in and try to fertilize the same eggs.

SUZANNE GRAY (Simon Fraser University, British Columbia):
It happens really, really fast, and if the male detects other sneakers, other cuckolders in the area, that is when he is most likely to eat the eggs.

Gray says other kinds of fish also cannibalize their eggs, but usually to avoid either starving or caring for another fish’s offspring. In this case, there’s no obvious food shortage, and the males of the species don’t care for the eggs anyway. So it’s intriguing to ask what the cuckolded males might gain by eating the eggs, besides a free lunch.

I’m Bob Hirshon, for AAAS, the science society.