How do dolphins do it?
Yes, we mean 鈥渋t鈥� 鈥� sex.
For the most people, how dolphins copulate probably isn鈥檛 a topic that comes to mind often, if ever. Dara Orbach isn鈥檛 most people.
鈥淚鈥檓 really interested in the mating strategies and behaviours of dolphins, whales and porpoises,鈥� says Dr. Orbach, a Killam postdoctoral fellow in Biology at Dalhousie, working with Hal Whitehead's team.
After the topic piqued her interest at a marine mammal conference in 2009, she鈥檚 spent much of the past seven years studying the sexual activity of cetaceans, the class of aquatic mammals that includes species like dolphins.
This past weekend, Dr. Orbach presented her team鈥檚 findings at the American Association of Anatomists conference in Chicago. Subsequently her work has been covered by Science Magazine, National Geographic, Discovery Channel, Newsweek, the CBC and more.
Bringing it all together
Dr. Orbach and her co-authors 鈥� Patricia Brennan of Mount Holyoke College, Diane Kelly of the University of Massachusetts-Amherst, and veterinary radiologist Mauricio Solano of Tufts University 鈥斕齭tudied the physical side of dolphin intercourse.
鈥淲e wanted to understand how male and female genitalia fit together during copulation,鈥� says Dr. Orbach.
If you think that sounds difficult to do, you鈥檙e right. To study cetacean sex, Dr. Orbach has permits that allow her team to receive and study the genitalia of marine mammals that have died of natural causes.
鈥淔emale cetaceans have unusual folds in their vaginas of unknown functions,鈥� explains Dr. Orbach. 鈥淢ale cetaceans and their closest relatives have a fibroelastic penis, which means the erectile tissue is full of collagen and resistant to bending.鈥�
So the team created a silicone mold of the interior of the dolphin鈥檚 vagina, as well as a method to inflate the penis, then preserved it to maintain rigidity. They were then able to CT scan the penis inside the vagina to understand exactly how they fit together.
鈥淚t is important to study male and female genitalia at the same time because evolution acts on both of them together,鈥� says Dr. Orbach.
Understanding sex, supporting conservation
Dr. Orbach鈥檚 research shows that the body positioning of cetaceans may be critical to predicting which copulations lead to fertilization success.听 This research has allowed Dr. Orbach鈥檚 team to understand the role females may have in controlling paternity: by moving their bodies slightly, the male鈥檚 penis could be diverted into a position where the sperm has a longer distance to travel to fertilize the egg.
听
鈥淭here鈥檚 been a bias in the study of genital evolution,鈥� says Dr. Orbach, explaining that while there has been a fair bit of research conducted on male genitalia, female reproductive morphology has not been studied to the same degree. 鈥淔emales are thought to have a more passive role in controlling paternity.鈥�
Dr. Orbach hopes that her team鈥檚 research offers insights that could be expanded to other species, and that by better understanding how animals breed, scientists and conservationists alike can help conserve and support populations of endangered species.