I’ve been busy these past weeks/months working on a new writing project, but I just had to take a few moments today to answer an intriguing question I received from a curious reader. Especially since it involves a dolphin-science myth – something I always enjoy investigating. He/she writes:
“There’s this common myth about male dolphins having a ‘prehensile’ penis and this question probably have been asked several times before: While it is fibroelastic and retractable by penis muscles, thus having some flexibility, does the dolphin also have the ability to consciously control or manipulate and consistently hold the (vertical) angle of its genital when protruded? Would that be possible with the retraction muscles? Is there any (nearly scientific) material regarding this subject?”
Well, dear readers, I am by no means a dolphin anatomy expert, but I did some poking around and came up with what I hope is a satisfactory answer. Here was my reply:
The definition of prehensile involves the ability of the appendage to grasp onto something. By that definition, there are no cetacean penises that are truly prehensile as far as I know. For the dolphin penis, however, there are muscles attached to the penis (some that that are anchored in the pelvic bone) that allow the dolphin some (conscious) control/movement of the penis – from the ability to extend and retract it, to the ability to move it around in various directions. The engorging of the penis with blood during arousal is unconscious (like in most mammals), but the extension/retraction of the penis and its movement once extended is under conscious control. I don’t believe any species has the ability to truly wrap their penis around something. I’ve heard dolphin trainers talking about rather flexible harbor porpoise (Phocoena phocoena) penises that wrapped themselves around their arms. I am not sure what wrapped might mean in this context though as it’s a bit in the eye of the beholder. My guess is that most species can probably direct their penises somewhat, but don’t have the ability to wrap them like you see with a prehensile monkey tail or elephant’s trunk. There is an article detailing a mating event involving right whales where you can clearly see the males “directing/bending” their penises to copulate with the female. But this is more of a bending than a wrapping.
Here is a recent scientific article that discusses the musculature around cetacean (including dolphin) penises: Dines JP, Otárola-Castillo E, Ralph P, Alas J, Daley T, Smith AD, and Dean MD (2014) “Sexual selection targets cetacean pelvic bones,” Evolution doi:10.1111/evo.12516
Final note: if there are any dolphin penile anatomy experts out there who’d like to clarify this wrapping vs bending thing, feel free to drop me a line.
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