Nudibranch sheds penis after sex

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Nudibranch sheds penis after sex

February 19, 2013 - 10:51
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A Japanese research team discovered the nudibranch Chromodoris reticulata loses its appendage after mating and can regrow it in a relatively quick time period to do it again.

The nudibranch Chromodoris reticulata sheds and regrows its penis between matings.

Nudibranchs are hermaphrodites, meaning that they carry both male and female reproductive organs. Moreover, when they mate, they can perform the male role of donating sperm and the female role of receiving sperm at the same time.

The scientists observed sex between sea slugs that they had captured during scuba dives and held in a tank.

It goes both ways

This process involves two penises and two vagina-like organs, and sperm transmission effectively happens simultaneously during the encounter.

After each coupling, which lasted between dozens of seconds and a few minutes, every slug discarded its penis - a thread-like organ that it projects from its side into a partner’s vagina.

The team also examined the microscopic structure and function of the male organs - observing an internal spiral structure they believe grows into a replacement penis.

Chromodoris reticulata may compensate for the short-term cost of decreased reproductive opportunities caused by the loss of a penis with the reproductive advantage gained by sperm displacement.

n another revelation about the sea slug’s sex life, the scientists found its penis was covered with spines - and suggested these may be used to remove the sperm of previous partners being held in store by their mate.

The spines are backward-pointing, making it difficult to withdraw the penis after copulation. This may explain the organ’s disposable nature.

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