For the lowly flatworm, penis fencing is no laughing matter

Have you ever wondered how flatworms— you know, those billowing tissue-like invertebrates — reproduce? Well, certain Platyhelminthes engage in a behavior known as "penis fencing," which involves two hermaphroditic creatures dancing a bizarre sexual tarantella in hopes of impregnating their opponents. Explains PBS of… »1/13/12 2:15pm1/13/12 2:15pm