Meet the Argentine lake duck—a small bird with one oversized surprise. Males boast the longest penis relative to body size in the bird world, reaching up to 16.7 inches, often longer than their own bodies. This corkscrew-shaped organ helps navigate the complex reproductive anatomy of female ducks.

Why the extreme anatomy? It’s part of an evolutionary arms race. In a world where forced mating is common, males developed longer penises while females evolved complex counter-defenses. Survival depends on adaptability—and flexibility.

But it’s not all drama. These ducks also engage in head bobs and soft calls to woo mates. In the water, they're agile swimmers, using their stiff tails to dive for insects and plants.

Native to southern South America, especially Argentina, this duck is a bold example of how far evolution can go in the name of survival.