Thursday, May 14, 2015
Would you like to have a 17-inch penis? Be a duck.
The Argentine lake duck has something to quack about. Its penis can be 17 inches long, proportionally the longest of all vertebrates. It's especially impressive among birds: Most male birds don't have penises, and instead mate by briefly touching genital openings with females.
The Argentine lake duck has a corkscrew-shaped appendage, which mirrors the female’s oppositely corkscrewed vagina. No one knows why this duck evolved a gigantic member, but some researchers have speculated that the giant penis may be an example of "runaway" sexual selection, where female preference drives male anatomy to extremes, as in the peacock's tail.