For years, scientists have puzzled over the ridiculously long, curly penises of some duck species. When it's not mating season, duck penises are tiny - the size of a grain of rice. But when it's time to impregnate a mate, duck penises grow into twisted organs, sometimes longer than the duck's entire body!
Until behavioral ecologist Patricia Brennan began her project to dissect the genitals of ducks, no one could explain why this happened. But when Dr. Brennan cut open her frist female duck, she found the answer.
Apparently long phalli are just an evolutionary answer to female duck genitalia. It turns out that female ducks have vaginal tracts just as curly and complicated as their mates' penises. Though ducks tend to pair off and mate for an entire season, female ducks also face less welcome suitors -- up to 40 percent of copulations are forced upon them by aggresive males. But because of the labyrinthine nature of her genitals, a female duck can capture unwanted male sperm in sacs along her oviduct and then expel it. Long penises are the only way for a mate to steer his way throught hte vaginal maze, Brennan tells The New York Times. "Basically, you get a bigger phallus to put your sperm in farther than the other males."
Among the scary things a kid can say to his parents: "Mom, I want to dissect duck genitalia when I grow up"!!!!!!!!