How Can You Tell a Female Animal From a Male?

When females have "penises," determining who's who can be tough.

These African predators are known for being tricksters—even when it comes to their genitalia.

Female spotted hyenas "have an elongated clitoris that closely resembles the penis of a male,” Sarah Benson-Amram, a zoologist at the University of Wyoming, says by email.

These pseudo-penises or pseudophalluses, as they're called, are paired with "testicles"—actually fused labia filled with fatty tissue.

So how can a layperson tell female and male spotted hyenas apart? Here's a tip.

Both sexes get erections when they're excitedly greeting each other, Benson-Amram says.

“If the tip of the erect phallus is pointed, it’s a male; if it’s blunt and straight across, it’s a female.” (Also see "Fossil Daddy Longlegs Sports a 99-Million-Year Erection.”)

Even so, such a small detail can

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