This is a female insect -- and scientists say that is her "penis."
That's right. Scientists say they've discovered four species of Brazilian cave insects with sex-reversed genitalia. The females possess a penis-like organ, the males a vagina-like organ.
This is the first documented example of animals with sex-reversed genitalia.
Sex-role reversal has been observed previously in animals -- such as in African antelopes. But the "female penis" seen in the four species, all of which are in the genus Neotrogla, is a "completely novel structure," Kazunori Yoshizawa, an associate professor at Hokkaido University and one of the scientists behind the new finding, told The Verge. "These females likely represent the most ‘macho' females among animals discovered to date."
How do these insects have sex? During copulation (pictured above), the female Neotrogla inserts a "highly elaborate" penis-like organ, dubbed the "gynosome," into the male's vagina-like opening. The female insect's spine-covered "penis" then latches onto the male's internal tissues as it gathers sperm for fertilization. The whole process can take awhile -- from 40 to 70 hours.
In a paper describing their finding, the researchers said that "the insects' sex organs and sex-role reversal may have been driven over evolutionary time by the resource-poor cave environment in which the bugs live."
Why? In addition to providing for reproduction, the males' sperm may provide nutrients to the females.
The researchers -- who told National Geographic they were "astonished" by the discovery -- are now conducting further studies in hopes of learning more about the insects and their strange sex organs. The bugs may yield new insights into sexual selection and the evolution of genitalia.
The paper was published in the journal Current Biology.