Either that or a pony

Scientists recently discovered that the females of four insect species living in dry caves in Brazil have what some ambitious women have always yearned for: a penis. "Because the female anchoring force is very strong, a male's strong resistance may cause damage to his genitalia. Therefore, it is very likely that entire mating processes are controlled actively by females, whereas males are rather passive," said entomologist Yoshizawa Kazunori, the lead scientist.

The females have an elaborate, penis-like organ while the males have a vagina-like opening into which females insert their organ during mating sessions that last 40 to 70 hours, the scientists reported in the journal Current Biology. The researchers said these attributes make the four species of the insect genus Neotrogla unique in the world.

Yoshizawa said that although sex-role reversal has been documented in several different types of animals, these insects are the sole example in which the "intromittent organ" – the male sex organ – is reversed. The scientists call the female penis-like structure a gynosome. During mating, a female inserts it into a male and receives sperm. Once inserted, part of the gynosome inflates and spines internally anchor the male and female insects together.

Yoshizawa cited other unusual examples of sex organs among animals, including female seahorses that use an organ to deposit eggs within a male's brood pouch and a kind of mite whose females have a long genital tube. By the definition of female – an organism that produces egg cells that are larger than the sperm cells produced by males – "even with the penis-like intromittent organ, females of Neotrogla are still female," Yoshizawa said. But Yoshizawa added: "Females of Neotrogla likely represent the most 'macho' females among animals discovered to date."

(Courtesy of Numbers the roach.)