Crazy in Love: Why Some Animals Eat Their Mates

Mating can be a dangerous game in the animal kingdom. In rare cases, mates may end up not only dead—but also eaten! The tendency for females to eat their male mates, known as sexual cannibalism, has been observed in several animals… …including some species of mantises, black widow spiders, and even octopuses. While it may seem like a counterintuitive evolutionary practice, scientists have proposed several theories to explain why eating one’s mate is a positive. For females, the benefit may lie in the extra fuel that comes with eating the male. Species with a long gestation period, such as the green anaconda, may consume a male mate to obtain an energy reserve to use while their limited movement during pregnancy makes hunting difficult. Other species that give birth to many young at once may also need the extra energy. Female scorpions may eat their mates because they need extra energy to give birth to as many as 100 live young. For males, sacrificing their bodies may increase the chance that their genes are passed on. Studies have shown that being eaten can prolong the amount of time spent mating, which increases the chance of fertilization. In some species, females may also not mate again for a period of time after eating a mate, reducing competition between the deceased male and others. And the extra fuel that a male’s body provides may lead to a larger number of hardy offspring, helping his genes survive beyond his lifetime. So while the loss of life may seem like a hefty price, it may actually be a significant investment to ensure a species's long term survival!