Dolphin sex isn’t just about babies


World-first examination of dolphin genitalia suggests copulation is as much about bonding as babies. Andrew Masterson reports.


A computer reconstruction of the clitoris of bottlenose dolphin.

Dara Orbach, Mount Holyoke College

World-first examinations of the dolphin clitorises suggest that sex may be a pleasurable exercise for the marine mammal, and thus an important social bonding behaviour.

Dolphins, including the bottlenose (Tursiops truncates) are members of a small group of mammals that are known to copulate year-round, including during periods when conception is impossible.

In other members of this select band – such as humans and bonobos – the behaviour has long been recognised as having strong social relevance, and a purpose that goes way beyond simple procreation.

Now, researchers led by Dara Orbach from Mount Holyoke College in the US, say it appears that dolphin sex may serve a very similar role.

The conclusion comes after a detailed study of the gross and microscopic structure of a number of bottlenose dolphin clitorises. The organs were collected from 11 deceased specimens found by the US National Marine Fisheries Service.

Orbach and colleagues found that a dolphin clitoris has a tissue structure that is likely to expand when stimulated, and also contains bundles of nerves that suggest high levels of sensitivity.World-first examinations of the dolphin clitorises suggest that sex may be a pleasurable exercise for the marine mammal, and thus an important social bonding behaviour.

Dolphins, including the bottlenose (Tursiops truncates) are members of a small group of mammals that are known to copulate year-round, including during periods when conception is impossible.

In other members of this select band – such as humans and bonobos – the behaviour has long been recognised as having strong social relevance, and a purpose that goes way beyond simple procreation.

Now, researchers led by Dara Orbach from Mount Holyoke College in the US, say it appears that dolphin sex may serve a very similar role.

The conclusion comes after a detailed study of the gross and microscopic structure of a number of bottlenose dolphin clitorises. The organs were collected from 11 deceased specimens found by the US National Marine Fisheries Service.

Orbach and colleagues found that a dolphin clitoris has a tissue structure that is likely to expand when stimulated, and also contains bundles of nerves that suggest high levels of sensitivity.

“In dolphins, the clitoris is positioned at the entrance of the vaginal opening and in direct contact with the penis during copulation, unlike the external position of the clitoris in humans,” says Orbach.

“The location of the clitoris near the vaginal opening indicates it can potentially be easily stimulated during copulation.”

Orbach presented her team’s findings over the weekend at the annual meeting of the American Association of Anatomists, held in Orlando, Florida, in the US. A journal paper is in the works.

And while dolphin sex organs might seem like a recondite and perhaps frivolous choice of research topic, Orbach is quick to point out that it has serious implications for the whole field of zoology.

“Very little is known about female reproductive morphology in most wild vertebrate species,” she says.

“This research provides a comparative framework to explore other functions of sex that may not be unique to humans. We are on the precipice of a deeper understanding of the relationship between form and function of genitalia.”

“In dolphins, the clitoris is positioned at the entrance of the vaginal opening and in direct contact with the penis during copulation, unlike the external position of the clitoris in humans,” says Orbach.

“The location of the clitoris near the vaginal opening indicates it can potentially be easily stimulated during copulation.”

Orbach presented her team’s findings over the weekend at the annual meeting of the American Association of Anatomists, held in Orlando, Florida, in the US. A journal paper is in the works.

And while dolphin sex organs might seem like a recondite and perhaps frivolous choice of research topic, Orbach is quick to point out that it has serious implications for the whole field of zoology.

“Very little is known about female reproductive morphology in most wild vertebrate species,” she says.

“This research provides a comparative framework to explore other functions of sex that may not be unique to humans. We are on the precipice of a deeper understanding of the relationship between form and function of genitalia.”

  1. https://plan.core-apps.com/eb2019/abstract/fc3c5a76-2dab-4997-af46-25f331877a19
  2. https://www.anatomy.org/
  3. https://plan.core-apps.com/eb2019/abstract/fc3c5a76-2dab-4997-af46-25f331877a19
  4. https://www.anatomy.org/
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