Male spiders "castrate" sex organs to increase chance of paternity

Male spiders break off their sex organ during intercourse with a female to increase chances of paternity.

Research shows that some males "castrate" themselves so the organ can keep injecting sperm long after they have scuttled off.

Their tendency to make a swift escape is due to females' tendency to eat their mates.

A team wrote in the Biology Letters journal that the castrated sex organ acts as a "plug", despite rendering the insects sterile.

This is said to prevent other males from mating and creating offspring with their chosen female.

In explaining the phenomenon, the study concludes that voluntary castration evolved as a response to two factors - female cannibalism of male spiders after sex as well as a counter to the female's desire to control the duration of sexual intercourse.

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