Humans do some pretty freaky stuff in the bedroom, but it usually falls short of decapitating and eating each other. Some of our cousins in the animal kingdom do not avoid these trifling taboos.
"When you're talking about cannibalism, it's not cut-and-dry Jefferey Dahmer -- it's not just a starving creature, or animals cannibalising each other because they're stuck in a cage," Bill Schutt, author of the new book Cannibalism: A Perfectly Natural History, explained to Gizmodo.
Schutt's book details various instances of animals for whom lovemaking and mealmaking are one in the same. For those who can't stomach an entire book on this subject but are still looking for a little freaky animal porn, we've listed a few of our favourite examples below, along with illustrative videos. I do not suggest you try any of these positions at home.
It's common knowledge that mantises eat their partners while mating, but this doesn't happen all the time, according to Schutt -- generally, full-stomached females don't feel the need to feast on a partner picnic. In fact, one study found that less than a third of female praying mantises eat their mates in the wild. Another species of giant Asian mantis males have tailored their behaviour to avoid becoming sex food. It seems that in general, males are not getting eaten all the time.
Interestingly, Schutt says, some males mantises appear to retain the ability to keep on thrusting, even after losing their head. Decapitation might cause involuntary contractions in the headless male mantis' abdomen, increasing the odds of fertilisation.
So, rather than a regular occurrence, think of mantis sexual cannibalism as a sexy surprise, like wearing your partner's favourite underwear or cologne.
Some female spiders, including the black widow's cousin, the Australian redback spider, frequently eat their tiny male partners during an elaborate mating ritual. The penis-less male spiders have appendages on their fronts used to deposit sperm into the female spider's lady parts. While doing the sex, the male flips over and puts his abdomen into the female's face for her to take a bite out of it. Eventually, she seductively wraps her partner up, liquefies and consumes him.
So, what benefits are there to becoming love lunch? Schutt reports that the men who received the brutal rim job from their superior female partners seemed to last longer and bear more children. However, please remember that these are spiders, not humans, and thus not sufficient evidence to ask similar requests of your own partners.
I can't sum this one up any better than this image caption from a paper in Trends in Ecology and Evolution by German scientists Heike Reise and John Hutchinson: "After a double penetration, two banana slugs Ariolimax dolichophallus are taking turns gnawing off the one stuck penis."
Banana slugs are hermaphrodites, meaning they have both male and female reproductive organs. Sex involves one or both male organs penetrating the female organs, according to the same paper. It turns out the female organ is very good and holding onto the male organ -- so good that the giant penis can get stuck. Eager to get back to their day after the hours-long mating session, the two slugs will try to free themselves by chewing off the one partner's donger.
Others scientists don't think the chewing comes from a point of desperation, but rather could be a form of elaborate natural selection. The one who leaves the encounter with both a penis and an ovary full of sperm emerges the evolutionary victor, reports Cassandra Willyard for the blog Last Word on Nothing. However, the researcher behind this idea, Brooke Miller, doesn't think the evidence is conclusive.
Plenty of other species like octopuses, other insects and amphipods have been observed eating each other as a part of their dirty-doing, but I couldn't find any steamy video to accompany those encounters. So, for now, have fun out there, and try not to get eaten, boys!