SDMB Believe It Or...(Weird Facts You've Learned Recently)

[Dung_Beetle]

From a General Questions thread, this is the coolest thing I’ve heard lately:

@Chronos

And then there’s penis fencing, practiced by some flatworms. The worms are hermaphroditic, but in any given mating, one will take on the female role, while the other takes on the male role. Both get the same benefit from this, offspring, but it costs the mother a lot more than it does the father. So how do they decide who gets to be the dad? By penis fencing. The flatworm penis has a sharp point, and they jab at each other until one penetrates the other’s skin and inseminates it.