Male ducks have explosively uncoiling corkscrew-shaped penises, while female ducks have evolved complex, labyrinth-like vaginas with dead ends and reverse spirals to defend themselves against unwanted mating.

A closer look

Male ducks have explosively uncoiling corkscrew-shaped penises, while female ducks have evolved complex, labyrinth-like vaginas with dead ends and reverse spirals to defend themselves against unwanted mating. This intense evolutionary arms race occurred because duck mating is notoriously aggressive and often non-consensual. To maintain control over who fathers her ducklings, the female's anatomy literally functions as a biological chastity maze that can shut down the male's invasive corkscrew tactics. Next time you are throwing stale bread to those cute little quackers at the local park, just remember that underneath those picturesque feathers lies a horrific warzone of twisted genitalia and extreme reproductive warfare. It completely ruins the peaceful ambiance of a Sunday afternoon pond visit to know that ducks are out there packing tactical spring-loaded hardware just to navigate an anatomical escape room