A sea slug that is able to detach, re-grow and then re-use its penis has surprised scientists.
Japanese researchers observed the bizarre mating behaviour in a species called Chromodoris reticulata, which is found in the Pacific Ocean.
They believe this is the first creature known that can repeatedly copulate with what they describe as a “disposable penis”.
The sex life of the sea slug is complicated even before detachable organs come into play.
Almost all of these creatures, which are also known as nudibranchs, are thought to be “simultaneous hermaphrodites”. This means they have both male and female sexual organs and can use them both at the same time.
Bernard Picton, curator of marine invertebrates at the National Museums Northern Ireland, explained: “The genital apparatus is on the right hand side of the body. So two nudibranchs come together and one faces one way and one faces the other way, with the right hand side of their bodies touching.
“The penis from one fits into the female opening of the other one, and the penis from that one fits into the female opening of the first one, if you see what I mean.
“They are both donating sperm to the other one.”
But the finding that one species has added another layer of complexity to copulation surprised the sea slug expert.
“I haven’t seen anything like this before,” he said.
More: http://www.bbc.co.uk/news/science-environment-21431678