From spraying mates with urine to changing one's sex, these are the most intriguing courtships in the animal kingdom.

This tree-climbing giant is one of the largest land slugs on Earth – and its bizarre mating ritual is unlike anything else in the natural world.

Cats may bite, and geese may have barbed penises, but one newly described hermaphroditic sea slug has taken violent animal sex to a new level by stabbing its mates in the head. The perpetrator of this ...