It seems that flying isn’t the only unusual thing bats can do compared to other mammals. New research has discovered a species of bat whose males use their large penises as an arm during sex. Rather than engaging in penetrative sex, these bats and their genitals appear to engage in close-contact “kissing,” a method widely observed in birds but never before in mammals.
Bats are one of the most abundant groups of mammals, accounting for 20% of known species (just behind rodents). But there is still so much we don’t know about them, in part because of their nocturnal and isolated lifestyle. There have, however, been indications that bat reproduction may have its own peculiarities compared to other mammals.
In some species, for example, female bats are capable of store sperm collected before hibernating, allowing them to become pregnant after emerging from their sleep in the spring. Other species can delay the development of their fertilized embryos until the conditions for a successful pregnancy are better, such as having more food available.
The authors of a new study, published Monday in the journal Current Biology, they say their curiosity was initially sparked by a distinctive attribute found in male serotinous bats (Serotine of Eptesicus): their enormous smut.
“By chance, we had observed that these bats had disproportionately long penises, and we were always wondering, ‘How does that work?'” said lead author Nicolas Fasel, a researcher at the University of Lausanne in Switzerland , in a study. statement from Cell Press. “We thought maybe it was like in dogs where the penis gets engorged after penetration so they’re locked together, or maybe they just can’t get it to fit. “inner, but this type of copulation has not been reported in mammals until now.”
To find out, Fasel and his colleagues enlisted the help of a bat rehabilitation center in Ukraine and Dutch citizen scientist Jan Jeucken, both of whom had accidentally collected hours of footage of these bats in the during their day. And nestled within the footage was plenty of bat action. The team documented 97 such mating events, finding no evidence that these bats were having penetrative sex.
Instead, the bat’s penis enlarges before reaching the female bat’s vagina. During the mating process, in which the male clings to the female by the nape of the neck, the penis appears to sweep over the protective tail membrane surrounding the vulva and then remains pressed against her for an extended period of time. The average duration of these sexual encounters was about 53 minutes, but the longest recorded bout lasted more than 12 hours.
The team also studied living and dead serotine bats in the lab, confirming a few other genitalia-related traits. For example, the penises are about seven times longer than the vaginas of female bats, while the heads of these penises are heart-shaped and about seven times wider than the vaginal opening. Women’s cervixes are also unusually long, which could help their bodies store or be more selective about the sperm that inseminate them.
Overall, the evidence points to a long-standing arms race between male and female serotine bats over how they mate.
“Bats use their tail membranes to fly and capture insects, and bats also use them to cover their underparts and protect themselves from males,” Fasel said, “but the males can then use these large penises to overcome the caudal membrane and reach the vulva.
The researchers note that their findings currently only indirectly suggest that serotine bats use this method to mate. The abdomens of female bats appeared wet after these episodes, indicating for example the presence of sperm, but the team could not prove that the sperm had been transferred during the act, and that this transfer had then leads to a successful pregnancy.
The team plans to pursue more in-depth research that will study serotinous bat mating closely, in a naturalistic setting. They also hope to study whether this mating strategy occurs in other bat species.
“We’re trying to develop a bat porn box, which will look like an aquarium with cameras everywhere,” Fasel said.