雄性蜘蛛的下场

To a female orb web spider, a suitable male can look like a mate—and a meal. For these spiders, the dating game has turned into a deadly dance of evolutionary one-upsmanship.

The female spider can choose when to cut off intimate relations by eating her partner, or kicking him out. This dynamic has led males to an unlikely strategy to make sure they have some say in the matter: self-castration.

Males are able to leave part or all of their organ inside of a female, which decreases the odds the female will be able to mate again. But new research shows that when a male leaves his whole kit-and-caboodle behind, his likelihood of fathering the next batch of eggs is much higher. Why? His parting gift keeps on giving, even after he is gone.

This remote-copulation technique actually boosts the amount and speed of sperm transferred to the female. The behavior is described in the journal Biology Letters. [Daiqin Li et al, Remote Copulation: male adaptation to cannibalism, link to come]

So for these unlucky fellas, it is better to have loved—and lost.

—Katherine Harmon