Meet The Sea Bunnies, The Strange Sea Creatures Japan Has Fallen In Love With

The sea bunny, like most sea slugs or nudibranchs, is a hermaphrodite. They have both male and female reproductive organs, and when they mate, both partners exchange sperm. The cuddly-looking creatures come armed with incredibly long copulatory spines, says Valdés. It's basically like a dart that the animal jabs into its partner during the mating process. This ensures that they stay attached to each other until the sperm exchange is done, he explains.