A surprisingly large number of animals kill each other after sex

Katherine Ellen Foley reports on the curious phenomenon of sexual cannibalism in the animal kingdom.

But octopuses aren't the only ones who kill their sex partners. Female praying mantises often kill their mates, especially if they're hungry, and within certain species of spiders, the males will actually offer themselves as a meal for their newly-impregnated partners.

Despite the ferocity of mating in the animal kingdom, romance is not dead: sexual cannibalism can be something of a gift from the male to the female in many cases. Female wolf spiders and tarantulas, who often eat males pre-intercourse, produce 30% more eggs than those who don't when they finally get around to mating. And in the mantis' case, the death of one male often means the survival of the reproducing female.

"It's probably not the male's preferred outcome," Scheel says. "But if you think about it…contributing his calories to his offspring doesn't do any harm [to the species]."