The Female Animal That Has a Penis

It's the first time this has ever been observed.

This ain't how it normally works. Image: Current Biology

We’ve seen a lot of crazy things when it comes to how animals reproduce and rear their children over the past couple years—male guppies that grow claws to grab their mates, angler fish fusion, penis fencing in flatworms, and, of course, duck penises—but scientists have just found a new first: A female animal with a penis.

Neotrogla, a cave insect that lives in Brazil, has completely reversed genitalia—the first time that’s ever been seen in an animal. It works about how you might expect, if you were asked to wonder about such things. The female has a penis that enters the male, literally grabs the sperm out of it, and returns it to her body. Neotrogla sex lasts, on average, between 40 and 70 hours.

The female gynosome. Image: Current Biology

As I’ve already mentioned, there are some animals that have rare sexual behaviors—the female anglerfish absorbs the body of the male when they mate, seahorse fathers carry the baby to term—but, in general, sex works pretty much the same across all animals, with the male, in some way or another, shooting sperm either directly into the female or shooting it into a place where she can grab it. Not so with these insects.

The female penis, called a gynosome, is “erectile, basally membranous, and apically sclerotized [hardened]. Its sclerotized part consists of a proximal rod-like extension and penis-like distal prominence. The latter encloses a duct leading to the sperm storage organ,” reports Kazunori Yoshizawa, a researcher at Hokkaido University in Japan. He published his findings in Current Biology

During sex, the hardened part of the penis “deeply penetrates the male, and its tip fits the opening of the seminal duct. The membranous part inflates within the male genital chamber, and numerous spines on the membrane internally anchor the female to the male.”

A diagram of how sex works—the female penis goes into the male and literally grabs sperm from the seminal duct. Image: Current Biology

This is, as I’ve already said, completely unprecedented. And researchers aren’t exactly sure why it works like this. They suggest that it may have something to do with a reversal of how evolution normally works—males compete for females. In neotrogla, females may have been forced to compete for males, so they literally grabbed onto them, for, like, 70 hours at a time.

But hey, it works. Good for them.