Scientists unraveled the mystery of an animal's unusually large reproductive organ, thanks to a Dutch retiree's recordings of bat mating in a church attic. Researchers from the University of Lausanne found that the bat species utilizes its elongated appendage uniquely during reproduction, eliminating the need for penetration.
Their study, titled "Mating without intromission in a bat" published in the journal Current Biology, focused on the serotine bat, whose reproductive organ is approximately seven times longer than its mate's corresponding anatomy.
Serotine Bats Use Its Oversized Member in Unusual Reproductive Behavior
Mammals, like bats and humans, typically undergo internal fertilization for gestation, with male anatomy evolving to aid sperm delivery near eggs during mating. However, certain animals, like songbirds, use a specialized opening called the cloaca for both reproduction and waste excretion, engaging in a 'cloacal kiss' to transfer sperm.
Mihaela Pavličev, an evolutionary biologist at the University of Vienna, notes the uniqueness of sperm transfer without penetration in mammals, making the observed behavior in the serotine bat unprecedented.
The study was initiated when Nicolas Fasel and colleagues at the University of Lausanne discovered the serotine bat's notably large and unconventional penis, constituting 22% of its head-body length when erect.
By chance, Fasel received an email titled "Eptesicus penis" with a video attachment from Jan Jeucken, a bat enthusiast monitoring a bat population in a church attic in the Netherlands. These unique videos, capturing bat copulation, prompted the analysis of 93 mating events in the church attic and four instances in a bat rehabilitation center in Ukraine.
During copulation, the male serotine bat bites the female's neck, likely for grip, and then maneuvers his erect penis around her tail membrane in search of the vulva. Despite the absence of penetration, the researchers infer that sperm likely reaches the vagina. While the longest observed copulation lasted 12.7 hours, half were 53 minutes or less.
Post-mating, the wet belly fur of the female suggests the presence of semen, although it wasn't sampled for confirmation. Nevertheless, Pavličev contends that the evidence strongly supports the researchers' interpretation of the behavior.
Bizarre Bat Mating Strategies Prompt Innovative Research Methods
Patty Brennan, a biologist at Mount Holyoke College not involved in the study, described the reproductive strategy as unusual, emphasizing the diverse and undiscovered reproductive behaviors of bats. Fasel speculated that female bats might use their remarkably long cervixes to retain sperm from multiple males for months before selecting a mate for reproduction.
The study suggests the possibility of other bat species engaging in non-penetrative mating, prompting Fasel to highlight the need for additional research on various species with unique penises. The authors underscored the discovery of a novel copulatory pattern in mammals, calling for further investigation into male competition and the role of pre-and post-copulatory female choice.
To explore the mating behavior of serotine bats further, Fasel and his colleagues are working on creating a bat porn box, resembling an aquarium with extensive camera coverage, as reported to LiveScience.
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