As mating rituals go there’s not much weirder than seaslug sex says Stuart Blackman

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Published: Wednesday, 31 July 2024 at 10:10 AM


Sea slug intercourse is notoriously unconventional says Stuart Blackman.

These hermaphrodite mollises are renowned for their dashing bouts of penis-fencing, whereby courting couples endeavour to fertilise their partner’s eggs by stabbing each other with their sabre-Me penises – without being speared in return.

But it turns out that the whole process is even more ferocious than previously imagined.

Because a species Siphopteron sp. has been found to wield two ‘swords: While one is used for injecting sperm in the normal (for sea slugs) way, the other is aimed solely at the partner’s head.

Should it hit its target, the slug then injects substances secreted by the prostate gland. Their function is not entirely clear, but they are believe to target the central nervous system – to quite literally brainwash the mate into preferentially accepting the assailant’s sperm.