Tuesday, June 12, 2007

Flatworm Penis Fencing! (Video)

During penis fencing, each flatworm tries to pierce the skin of the other using one of its penises. The first to succeed becomes the de facto male, delivering its sperm into the other, the de facto female. Mating is a fight because the worm that assumes the female role then must expend considerable energy caring for the developing eggs.



read more | digg story

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