In what just might be the most disturbing post-coital ritual on the planet, male ornamental tree trunk spiders (a.k.a. coin spiders) have a habit of biting off their own genitals.
While many types of spiders suffer damage to or even lose their palps — essentially, the spider’s penis — during sex, these spiders really, really, really want to make sure the things are gone. So whatever hasn’t been damaged during the act usually gets chewed off afterward.
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As it turns out, having no palps makes the male coin spider lighter, more aggressive and a better fighter. As a result, he’s better able to fight off any rivals making spider-eyes at his mate.
Kunter told New Scientist that mating just once carries another advantage for the males: fewer attempts at sex with a hungry female means a lower risk of being eaten.
