Scientists in Brazil have discovered a species of insect that breaks all gender norms: the females have penises and the males have vaginas.

The gender-bending female insects have penises with spikes that anchor the female into the male. During their 70-hour mating sessions, the spiky penises suck sperm out of the male vaginas.

"There's nothing that [this] can be compared to," study co-author Rodrigo Ferreira told National Geographic. "This elaborate female penis is completely unique."

Ferreira's research was published April 17 in the journal Current Biology.

Ferreira, who is a cave specialist at the Federal University of Lavras in Brazil, collected the bugs in the caves of western Brazil in 2010. They were sent to a lab in Geneva, Switzerland, where it was determined that the bugs belong to a new genus of insect called Neotrogla.

The species, which is only the size of a flea, mate with the female on top, probing its genitalia into the male.

The penis, which is called a "gynosome," is prickly; on three of the species, it has spines, and the fourth one has small bristles. The spines fit into the pockets in the walls of the male's vagina.

It was determined that the penis spikes and bristles are designed as an anchor to keep the male in place, because if the male is pulled from the female while mating, it will rip in half.

Therefore, the males cannot resist mating because it could rip them in half if they try and stop the mating while its in progress.

The unique species is the first of its kind that's been discovered. Some other species, such as a female seahorse, use a protruding appendage to put eggs in the male, but researchers wrote that it "is not a penis."

While the origin of the female penises is not yet known, scientists suspect that it could have something to do with the species living in caves with low food supplies.

The pockets where males store sperm also contains nutrients, meaning the females could have developed penises to extract nutrients out of the males' vaginas.