A girl's gotta eat, right?

Okay, let's face it - sex can be exhausting! For the guys the stressful part often is over after courtship and the actual act but if that was "successful" it's only beginning for the ladies - at least when they practice internal fertilization, egg-squirting fish are fine here. So when you have to nourish eggs or young it just makes sense to get a good protein-rich meal before, after or even during sex. And that's why female mosquitoes suck blood while the males are content with sugary plant juices. It is also why in some insects only female adults eat at all while the males prefer to be better flyers with an air-filled intestine.

But of course it would be much nicer if the guy invited her to dinner before having fun with her, right? It often works that way with humans, I've been told, and many animal suitors actually do bring a tasty mating gift, too. Well, actually, some females seem to have noticed, they all do... At least when you are carnivorous and larger than him. And that is why many spider males are very careful when they approach their desired mate as they always have to wonder - horny or hungry? And of course, there is always the risk of her being both and eating you afterwards, getting the love and the meal - yes, I'm looking at you, black widow!

So while a bit of sexy cannibalism seems to be a good deal for the female, why do male animals risk getting eaten? Well, that might be very simple - sex means possibly getting eaten but no sex means no offspring, so the overcautious ones might be extinct very fast. But... this isn't the whole story. Because sometimes getting eaten might be the best thing that can happen to you - well to your genes of course as you will be eaten. But your offspring might have a better start due to their well-fed mother. So if your chances are slim of finding another mate investing everything, really everything in that one chance may be your best bet. And there are animals that seem to have perfected that investment!

In preying mantises sexual cannibalism isn't as prevalent in the wild as it is in captive conditions but it does occur in up to a third of matings. And as the head of the male is what she can reach it gets eaten first - and that makes the male mate more enthusiastically. Because, in mantises, the lower body controls the thrusts and the brain actually slows things down, so when you bite off the head, the rest of the body makes sure that in this act it gives everything it can. Well, it's the last chance, so that does make sense. But there is always someone topping that... Australian Redback spider males actually bend towards their mates after copulating, offering their abdomen as a snack. And those that get eaten have more offspring in the end...

Of course, some ladies know how tasty a mate can be but do have the courtesy not to eat the father of their children. Where several species of North American fireflies occur in the same region, females and males use different codes of flashes to attract partners of the right species. And some females switch the code they flash after mating to attract other males as a post-coital snack. It may not surprise you that the male fireflies tend to approach every apparent sexy female quite carefully...

So, guys - the next time a woman looks at you lusting, licking her lips - just make sure, you impregnate her before she bites off your head! It may not safe your life and your sons and grandsons might inherit your suicidal sex drive but at least there might be many of them...

Further reading: Sexual cannibalism (Wikipedia)