Duck

During Japan's 1,200-year meat-eating ban, people devised creative loopholes. They classified rabbits as birds by calling their ears "wings," dubbed wild boar "mountain whale" to pass it off as fish, and claimed ducks were fish because they had webbed feet.

Most birds lack a penis—both sexes mate by pressing a single opening called a "cloaca" together. Ducks are an exception: their corkscrew-shaped penises can reach 42.5 cm, rivaling their body length. Unlike mammals, they achieve erection via lymph fluid in about one second.