An aroused tapir’s manhood is so “large and ungainly,” Stancer says, “I actually have seen the male step on it and scream.” Maneuvering the organ into mating position involves many swings and misses. And yet, she says, the male “had to evolve to that size and shape to get where it needs to go” in the female’s lengthy genital tract to inseminate her. Another evolutionary adaptation: large flaps near the end of the penis that Stancer says “make a seal inside the female” so that tapirs can successfully breed underwater as well as on land.