Reproduction without invasion of the broad-winged bat – Le Monde

A broad-winged bat ( A snake bat (“Eptesicus serotinus”) in Spain, June 2014. MARIO CEA SANCHEZ/BIOSPHOTO

We knew that bats are not mammals like any other. They fly, guide themselves and hunt using ultrasound, exhibiting unique longevity and an unparalleled immune system that allows them to live with a wide range of viruses. As far as their reproduction is concerned, the approximately 1,400 known species of bats offer a veritable feast of curiosities to those interested in them. “Women have the ability to store male sperm for months, delaying ovulation, fertilization, fetal implantation and embryo development. “They are incredible,” marvels Nicolas Fasel, a researcher at the University of Lausanne and a specialist in bat reproduction. The males are not to be outdone, as the sexes once again show unprecedented diversity in size and shape, which the researcher and his colleagues have been studying for several years. “We are used to being surprised,” he admits.

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But this time the discovery of the properties of serotins, which he and his colleagues first described in a correspondence published November 20 in the journal Current Biology, surprised him. In this habitus of European stables and attics, the males have a penis of 1.6 to 2 cm, i.e. between a quarter and a fifth of their size. Equally impressive is that they have a 7.5 mm wide bulge at the end in the shape of a heart and are decorated with small hairs. However, the female’s vulva measures less than 2 mm. “We had a problem,” said Nicolas Fasel matter-of-factly.

Long time

To solve the problem, he used the installations developed by Jan Jeucken, an amateur naturalist, in Horst-sur-Meuse in Limburg, Netherlands. A colony of common broad-tailed crayfish (Eptesicus serotinus) has taken over a church that the researcher has peppered with cameras. Enough to monitor the love of these lovely flying mammals as carefully as possible. He added observations made at an animal care center in Kharkiv, Ukraine. In total, the lovemaking of 97 couples was recorded. With amazing results.

First of all, the duration: long, undeniable. Normally the male spends about fifty minutes with the female. But one of the pair remained in position for more than twelve hours. This position, “dorso-ventral,” consists of the male climbing onto the female’s back and biting her neck to prevent her from moving. And then the penis? One of the hypotheses was that the swelling occurred after penetration, locking the two participants in what we aptly call a “copulatory lock.” The pictures showed nothing of the kind. On the contrary, they found that the man was using his organ “like an arm,” the article said. By doing so, he spreads the membrane that connects the female’s tail and hind legs, opening the way for direct contact of the tip of his penis with the vulva.

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