Octopuses Mate With a Special “Sex Arm”

This octopus game of cat-and-mouse actually has a very important goal—mating. Male octopuses have a specially modified "sex arm" that they use to place a pack of sperm into the female's mantle cavity.

The female then lays her eggs in a hole or under rocks. Once they hatch, the tiny octopods float in the water for several weeks before returning to the bottom.