6 Animals That Eat Their Mates

An insect that displays sexual cannibalism is the mantis, although not all species practice it. Compared with male mantises, females are much bigger and stronger, and this makes it easy to capture their prey. Females send out a chemical signal of pheromones to attract males. When the male attempts to mate with the female, it is prone to being attacked. Even if the male mantis is decapitated by the female, the male is still able to mate, as nerves in its abdomen control the body. Giving birth takes a lot of energy from the female, as it may lay about 100 eggs. Therefore, eating the male gives the female the required nutrition to birth its offspring. Some species of mantis can reproduce asexually in a process called parthenogenesis, and eating the male can fuel this process.

The black widow spider is another animal that sometimes practices sexual cannibalism. Like mantises, male black widows are much smaller than females—generally less than half the female’s size. Females make webs that are covered with their pheromones. An attracted male then performs web reduction: it cuts parts of the web and masks the female’s scent with its own. For the male to mate with the female, it has to place part of its body between the fangs of the female. Obviously, this leaves it open to being eaten. However, some studies have shown that black widows rarely eat their mates in the wild and that this occurs more frequently in captivity.

For male jumping spiders, it’s “dance well or be eaten.” Female jumping spiders can mate only once, so they are very selective. For a female to choose a mate, the male has to impress it with dance moves. The male will jump around and wave its limbs all over the place. At the same time, the male also creates a song by beating parts of its body together. This sends vibrations through the ground that the female will pick up. Listening to these vibrations is pretty awesome even for humans, as the songs tend to have beats and different verses. If the female is impressed, the male is allowed to mate. If not...the male may get eaten.

Green anacondas have a very interesting mating strategy that might end with one or more males being eaten. Female green anacondas are polyandrous and therefore will mate with multiple males. This is done in what is called a “breeding ball,” where sometimes more than 10 males gather on a female and compete with each other to find the cloaca so they can mate. Breeding balls may last up to four weeks, by which time the female has most likely mated with many males. As is a trend in this list, female green anacondas are bigger and stronger than males. They have a long gestation period during which their movement is severely limited. Therefore, by eating one or more of the males after mating, they gain the nutrients they need to successfully birth their offspring.

Scorpions are also creatures that might eat their mates. The mother invests a great amount of time and energy in its offspring, birthing as many as 100 in a single brood. Unlike most nonmammalian animals, scorpions are viviparous, giving birth to live young instead of laying eggs. This takes even more energy. Because of this, males that remain near females after mating are sometimes killed and eaten, which provides sustenance to the female. As a last resort, scorpion mothers may even eat their offspring to survive.

The octopus is known for its intelligence, but did you know that certain species are also cannibalistic? Males have a specially modified arm, called a hectocotylus, that is used to inject sperm packets into the female. When the males are done, the female octopus often eats the male. Many species of male octopus die soon after mating anyway, so why not? Female octopuses protect their eggs and often die upon giving birth. Octopus cannibalism is not limited to just mating, however, as it is not uncommon for hatchlings to eat each other.