The Disposable Penises of a Nudibranch.
Little did I know, when I shot this critter, that it had a kinky talent of regeneration.
I say ‘it’, because nudibranchs are simultaneous hermaphrodites. During mating, the pair will impregnate each other. With the penis location on the right side, when the nudibranchs line up, they can inseminate themselves at the same time. The act takes anywhere from a few seconds, to a few minutes.
Post-coital observations (for Science) showed that as the nudibranches pushed away from each other, they ‘shed’ their penises.
In less than 24 hours, however, the nudibranchs had regenerated their penises and were able to mate again.
Apparently the reason for this being that a large amount of the penis is stored coiled up in a spiral inside their bodies, used to replace the missing part.
So what’s the advantage?
The researchers say that in the first act of copulation the penis may be used to remove any sperm left by any competitors that its partner has mated with.
With the first penis and the rival sperm then abandoned, the second penis can be used to inject the sea slug with another dose of its own sperm, ensuring that their genes are the ones that are passed on.
Photo: Samantha Craven
Journal Article: http://rsbl.royalsocietypublishing.org/content/9/2/20121150