Duck penises are long and corkscrew-shaped. This has been known for a while, but a new report in Proc. Roy. Soc. imputes the evolution of this bizarre structure — and the matching long oviduct in females — to sexual selection: specifically, sexual conflict. The male’s apparatus twists clockwise, the female’s counterclockwise, and so she has some control over the act . . . .
Anyway read about this result at Carl Zimmer’s Loom and Ed Yong’s Not Exactly Rocket Science. BE SURE to watch the videos (not for the squeamish!). They involve duck farms, sexual frustration, and kinky artificial oviducts. This kind of story is made for science journalists.
You’ll never look at a duck the same way again.
Fig. 1. The iconic image, reproduced endlessly. Sad to think that this guy died just so his dangling member could be shown to the world.
Brenna, P. L. R., C. J. Clark and R. O. Prum. 2009. “Explosive eversion and functional morphology of the duck penis supports sexual conflict in waterfowl genitalia,” Proc. Roy. Soc. London doi: 10.1098/rspb.2009.2139. (You’ll need a site license for access.)