Sex-Reversed Cave Bugs Pack Spiny Female Penises

Here they are in action. Current Biology, Yoshizawa et al.

And you humans think you're so kinky and inventive.

Meet the Brazilian cave insects of the Neotrogla genus. We're talking four distinct species here and they mark the first documented example of an animal with sex-reversed genitalia.

That's right, as detailed in this month's Cell Press journal Current Biology, the females "insert an elaborate, penis-like organ into males' much-reduced, vagina-like opening" during 40-70 hour lovemaking marathons.

"Lovemaking" is a bit anthropomorphic. This is, after all, the brutal world of insects. As the team of Brazilian and Japanese researchers discovered, the female inserts her phallic "gynosome" into the male and then the sex organ inflates, hooking a bevy of spines into the male's body to anchor the two insects together.

Scientists have observed sex reversal in other organisms, but this marks the first time they've uncovered the female penis. Let's have a look at the "gynosome" on its own:

The female penis of N. aurora.
Current Biology, Yoshizawa et al.

The gynosome doesn't deposit material like a male penis. Instead, it receives sperm as well as capsules of nourishment -- sort of gift or bribe to encourage lots of mating. And this very act of gift-giving, the researchers argued, likely drove the evolutionary development of the female penis to begin with -- a phallic arms race if you will.

About the Author: Robert Lamb spent his childhood reading books and staring into the woods — first in Newfoundland, Canada and then in rural Tennessee. There was also a long stretch in which he was terrified of alien abduction. He earned a degree in creative writing. He taught high school and then attended journalism school. He wrote for the smallest of small-town newspapers before finally becoming a full-time science writer and podcaster. He’s currently a senior writer at HowStuffWorks and has co-hosted the science podcast Stuff to Blow Your Mind since its inception in 2010. In his spare time, he enjoys traveling with his wife Bonnie, discussing dinosaurs with his son Bastian and crafting the occasional work of fiction.