Lots of animals take part in what humans might consider bizarre mating tactics, but one sea slug might take the cake: it stabs its partner in the head.
From an evolutionary and biological perspective, animals are driven to have sex in order to procreate. But there is a lot more to sexual relations between animals. Animal sex is at least as strange and varied as human sex. A male might copulate with many females. And female animals of many species can be choosy, too. Homosexuality is common. Monogamy is rare. And the animal kingdom is full of swingers. In short, with animals, sex can be wild.
A simultaneous hermaphrodite, the slug has both male and female reproductive organs that it uses simultaneously during sex. The male organ is a two-pronged penis equipped with spines.
Sea lampreys use a digestive enzyme called a bile salt as a sexual pheromone, excreting it through their gills after not eating for weeks.
For insects like aphids, a raindrop on their head is like a refrigerator falling on a human, so it behooves them to detect stormy weather and avoid such naughty acts.
Unlike many other animals, kangaroos have sex for a long time — up to 50 minutes. And the female has three vaginas, two of which are inseminated by the male's double-headed penis.
Seahorses have a sex role reversal, where males get pregnant instead of females. But how do they actually get busy and get pregnant in the first place?
Females of two bug species may have figured out a way to lessen their chances of being on the receiving end of their species habit of "traumatic insemination."