Researchers have found that serotine bats, possessing notably large genitals, engage in a unique form of mating distinct from other mammals. While most mammals mate through penetration, these bats employ a different approach.
Instead of inserting their genitalia directly, male bats utilize their sizeable genitalia to move aside the female’s tail sheath.
Following this, they press against the female’s vulva for an extended period, up to 12 hours. This unconventional method was detailed in a study published on Monday in the journal Current Biology.
Nicolas Fasel, the main researcher and an evolutionary biologist at the University of Lausanne in Switzerland, expressed curiosity about the disproportionately long genitals of these bats. He stated, “We had observed that these bats have disproportionately long penises, and we were always wondering ‘how does that work?’.”
It turns out that the usual way doesn’t apply here — at least not like in other mammals. The male bats have genitals that are seven times longer and wider than the females’ vaginal openings when they are erect. This substantial size makes traditional post-erection penetrative intercourse impossible, as reported by Live Science.
“We thought maybe it’s like in the dog where the penis engorges after penetration so that they are locked together,” Fasel said. “Or alternatively maybe they just couldn’t put it inside, but that type of copulation hasn’t been reported in mammals until now.”
Out of 97 mating events, none appeared to involve penetration
Fasel and his team examined video footage captured by cameras strategically positioned on a grid that allowed bats to climb. The cameras provided a clear view of the animals’ genitalia during mating.
The researchers observed 97 mating events in the attic of a Dutch church and at a bat rehabilitation center in Ukraine. However, none of these mating sessions seemed to include any form of penetration, according to Live Science.
However, the videos revealed a different approach to mating. The males were seen gripping females by the nape and adjusting their pelvis until their erect penis was pressed firmly against the female’s vulva.
After achieving this position, the males maintained complete stillness in this embrace for an average of 53 minutes. The longest recorded interaction lasted nearly 13 hours.
The researchers observed that the penises were already enlarged before making contact with the vulva. This ruled out the possibility of any form of pre-erection penetration, a phenomenon known to occur in dogs, as reported by Live Science.
Serotine bats develop erections under anesthesia
The researchers also took measurements and provided a detailed description of the erect genitals of live serotine bats. It was observed that these bats develop erections under anesthesia, revealing a distinctive “heart-shaped” swelling at the tip of the genitalia.
“The terminal swelling was adorned with a few short hairs and composed of two large erectile tissues,” the researchers wrote in the study. “We postulate that the hair present on the terminal swelling serves as a sensor to assist in finding the vulva.”