The Detachable Penis

A species of sea slug discards its penis after mating, then grows another the next day, a tactic that may have evolved to avoid passing on the sperm of competitors.  

By | February 14, 2013

The sea slug Chromodoris reticulata FLICKR, STEPHEN CHILDSAs hermaphrodites, the diverse group of brightly colored sea slugs called nudibranches are already considered unusual when it comes to sex. But one species does something particularly peculiar: Chromodoris reticulata detaches and discards its penis after mating, then grows another to go again 24 hours later, according to a study published this week (February 13) in Biology Letters.

Having collected the sea slugs from reefs off the coast of Okinawa, Japan, researchers observed the creatures mating in tanks. They saw that sea slugs that had recently mated could not do so again for at least 24 hours. Then they noticed the reason why: the sea slugs sloughed off their male sex organs around 20 minutes after mating, leaving them without the anatomy required to repeat the trick until it grew back a day or so later.

Closer examination revealed that the sea slugs had a tightly coiled spiral of reproductive tissue tucked inside their bodies. “We think this spiral is effectively a penis-in-waiting that will uncoil rapidly after penis disposal and grown into a new penis,” Ayami Sekizawa of Osaka City University, lead author of the study, told Nature.

No other animal is known to repeatedly copulate using disposable penises, and the authors speculated that the tactic may have evolved to avoid passing on rivals’ sperm stored in the mate’s vagina—which appears to get caught on the backward-pointed spines of the penis.

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Avatar of: Mrs. Science

Mrs. Science

Posts: 1

February 14, 2013

I gotta say as I am in my lab working on cures for breast and brain cancer, articles like this make science research look ridiculous. Someone is actually getting paid to do this research which helps no one. Amazing it was even worth your while printing it.

Avatar of: Biotech Exec

Biotech Exec

Posts: 1

February 14, 2013

Fascinating.  And who knows where a discovery like this might lead?

Avatar of: liquiskyy


Posts: 1

February 17, 2013

and King Missile already wrote him a theme song...

Avatar of: BioM Dr.

BioM Dr.

Posts: 1

February 24, 2013

Hi Mrs Science,

That's pretty harsh. But more importantly, it's also pretty narrow minded. My work in biomimetic theory and, more generally, in knowledge transfer between biology and all other disciplines, has, if nothing else, made the case for why we must explore the incredible diversity in adaptation the exists in our mind-blowing biological world. 

It has also shown me that we are absolutely terrible at not only transfering the knowledge to others but also at thinking creatively about the possibilities. 

You have demonstrated the key difficulty: even other biologists cannot always appreciate the implication of a discovery. We have to get better at elucidating them! 

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