For male widow spiders, mating is an infamously dangerous activity. In these species, which include the black widow and redback, the large females will often devour the smaller males during sex—hence the “widow” in their names. In some cases, the female catches the male while he’s trying to escape. But often, the male seems to welcome his fate, actively somersaulting onto his partner’s fangs.

There’s a reason for these suicidal gymnastics. In 1996, Maydianne Andrade found that sexual encounters between redback spiders are longer if the male allows himself to be cannibalized. By sacrificing his life, he can fill his partner with more sperm. The female keeps that sperm in two storage organs, and can control when she