That suggests that the folds allow the animals to control paternity, although further analyses will be needed to confirm that hypothesis. “This confirmed there is this antagonistic coevolution,” said Orbach. And their vaginas are the most complex of the four, with “a whole bunch of spiraling folds,” Orbach explained, “which just keep twisting around … a little bit like a corkscrew.”īut the really fascinating part was that the scans revealed how vaginal complexity could limit penile penetration. “An erect harbor porpoise penis goes up to its chin - or, where its chin would be, if it were not a marine mammal,” Kelly said. Harbor porpoises, despite being the smallest species by body size, had the largest penises. The differences in reproductive anatomy between the species were impressive. In total, they were able to simulate intercourse for four species of marine mammals: harbor porpoises ( Phocoena phocoena ), common bottlenose dolphins ( Tursiops truncatus ), short-beaked common dolphins ( Delphinus delphis ), and harbor seals ( Phoca vitulina ) - those were the only species they had high-quality male and female reproductive organs for (sadly, they did not have an intact orca vagina to pair with the larger-than-table-sized penis). They were also able to create digital 3D models of the penises and vaginas and simulate various rotations and positions to determine the deepest penetration possible. scan of an artificially inflated bottlenose dolphin penis (red) inside a dolphin vagina. After some preliminary struggles (learning the hard way that plastic carboys are not pressure-rated, for example), Kelly’s final design was a used, $35 beer keg filled with saline and modified to allow her to pump in nitrogen gas to achieve an optimal injection pressure. So inflating the marine mammal members required creativity. “We’re not talking hand-sized - we’re talking arm-sized, depending on the species,” Orbach added (“We did a killer whale, which was bigger than the table”). The cetacean dongs were “another matter altogether.” “Most of what I have done are really small - armadillos, rats and mice, voles and other small things - where you just have to have a little syringe and a teeny bit of pressure and you get your erect morphology very quickly,” Kelly explained. Then they brought on Kelly for her penile inflation expertise. Orbach turned to Brennan, a genital expert at Mount Holyoke College known for her work on ducks (and their terrifying penises ), and together, with a caulking gun and silicone, they created models called ‘endocasts’ of vaginas from Orbach’s collection of 140 frozen marine mammal genitalia (all collected from animals that died of natural causes). That meant to understand the animals’ vaginas, she needed their corresponding penises to see how they fit together during intercourse. “But as I started dissecting more and more reproductive tracts and looking at this amazing level of vaginal variability which had never been documented before, I realized this probably somehow coevolved with the penis,” said Orbach. She already knew that marine mammal vaginas are far more complex than anyone has given them credit for - lots of labyrinthine pockets, folds, and twists, which Orbach suspects may help females control paternity. Orbach, a postdoctoral fellow at Dalhousie University and research associate at Mount Holyoke College, had the vaginas ready. The goal: make the first 3-D CT scans of simulated intercourse of any marine mammal species using real, post-mortem genitalia - scans that were just published in a paper in Proceedings of the Royal Society B. “They have what’s called a ‘fibroelastic’ penis,” she explained, which means their penile tissue contains “ a lot of collagen, and it makes the penis, even when flaccid, very stiff and less extensible.”įinding a way around this hard problem is a large part of why Dara Orbach and Patricia Brennan brought Kelly on to the project. “It’s actually a real challenge to artificially inflate cetacean penises,” she told me. Yes, the size makes things difficult - it takes a lot more saline to fill a large penis than a small one - but it’s more than that. But whale and dolphin penises are a lot tougher - quite literally. Like most mammals, human penises are mostly fleshy, with lots of vascular space for blood to flow into to make the flaccid structure rigid with turgor pressure. Reinflating human penises postmortem is a relatively trivial feat, says Diane Kelly, a research assistant professor at University of Massachusetts and penis inflation expert. Perhaps the hardest part about studying marine mammal reproductive anatomy using organs collected from deceased animals is that they can’t get an erection the easy way.

Dolphin jelly