Girls will be girls and boys will be boys, but for the insects of the genus Neotrogla, it’s not so clear. Because in these species of Brazilian cave-dwellers, it’s the females with the penis and the males with the vagina.
Writing today in Current Biology, researchers for the first time describe a critter that has essentially traded sex organs. Females are equipped with a penis-like structure called a gynosome, which “deeply penetrates” the duct leading to the male’s sperm storage organ.
Once inside, the gynosome inflates, deploying spines that anchor the pair for sexual bouts lasting as long as 70 hours (not a typo). The connection is so strong, in fact, that researchers trying to pry a pair apart “led to separation of the male abdomen from the thorax without breaking the genital coupling.”
Now, in the animal kingdom, typically females are choosier about sex because producing eggs is far more costly than sperm. But in this species, it’s the females who assume the role of aggressive pursuer.
During copulation, she receives not only sperm, but also nutritious packages known as nuptial gifts. This is an invaluable resource in the barren caves the insects inhabit, so “sexual conflict over the donation of a nutritious seminal gift,” the researchers write, “is thus the most likely factor favoring the evolution of the gynosome.”
How’s that for a first date?