Animals have evolved many different ways of protecting themselves, from prickly quills and razor-sharp teeth to clever camouflage and sturdy shells. Now, scientists have discovered a surprising new technique that appears to be a defense mechanism: Some male octopuses use venom to avoid being eaten by their female mates.

Learn more about the mating of blue-lined octopuses - a treacherous ordeal involving sex, cannibalism, and sedation.

Male blue-lined octopi (Hapalochlaena fasciata) have been found to use venom on their sexual partners, as well as for the usual reasons of defense against predators and subduing prey. Killing the females would be counterproductive,