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 11:15am 1/13/12 11:15am

The oldest symbiosis between animals and bacteria

In the shallow waters of the ocean, hiding between the individual grains of sand, live flatworms known as Paracatenula. With neither a stomach nor internal organs, they survive using through a symbiosis with bacteria — in a relationship older than any ever found before. To gain energy, the worms essentially need the… » 7/01/11 7:30am 7/01/11 7:30am