German researchers discover spider 'chastity belt'

BERLIN, Mar 6 (Reuters) A new study by German scientists of spiders' copulation techniques found that males leave part of their sex organ inside their female partner as a sort of ''chastity belt'' to deter rivals.

''By breaking off parts of their intromittent organs inside a virgin female, males can reduce sperm competition and thereby increase their paternity success,'' the Bonn University researchers wrote in the journal ''Behavioral Ecology''.

After setting the tone by shaking the female's web, the male has only seconds to have sex before the larger female kills him. In over 80 per cent of cases, the tip of the male's genital organ breaks off inside the female.

This appears to be the result of a hasty getaway -- but also leaves behind a sort of chastity belt that keeps other males away, the study showed.

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