Sea Slugs Stab Partners in Head after Sex to Control Their Brains [Video]

A species of sea slugs living off the coast of Australia stab their partners after sex. Researchers say that the slugs hit their partners to establish a type of brain control over the other.

The bizarre creature in question is the Siphopteron species 1. These slugs are quite small when compared to their relatives, measuring just 2 to 4 millimetres long, New Scientist reported.

Sea slugs aren't the only organisms that include torture in their love-making ritual. Several other creatures enslave, rape and murder their significant others. Even domestic cats have penis barbs that are used to scrape and stimulate ovulation in females. The idea of traumatic insemination is to get the sperm in certain area of the female body.

Rolanda Lange at the University of Tuebingen in Germany has been studying sea slug mating habits for many years, reported The Scientific American. However, Siphopteron species 1 takes strange mating rituals to a whole new level.

The slug places the sperm in the female's genital tract and simultaneously punctures her head, injecting proteins close to her central nervous system.

Researchers collected 32 specimens of Siphopteron sp. 1, off the Coast of Lizard Island in Queensland, Australia. These slugs were kept in a lab, where they were divided into eight mating groups. The team found that usually the slugs mated in pairs. Occasionally, three slugs engaged in mating frenzy where all would try to inseminate each other.

The study team hypothesizes that the fluid forced in the brain might have compounds that may increase production of eggs or aid reproduction system. Also, the fluid may ensure paternity by eliminating the sperm of the female's former lover.

"And if that sound a little below the belt, bear in mind that Siphopteron is a hermaphrodite - any "female" thus manipulated will get a chance to wear the trousers next time round," according to a news release.

The study, which also included Johanna Werminghausen from Monash University in Melbourne and Nils Anthes from the University of Queensland, the Scientific American reported. The study is published in the journal Proceedings of the Royal Society B.