Nudibranchs are hermaphrodites, so an individual produces both sperm and eggs. Their genital openings are located just behind their heads on the right side of their bodies. Mating involves a two-way exchange: They mutually extend their penises and exchange sperm, leaving both animals with fertilized eggs. After mating, nudibranchs lay their eggs in long ribbons or strings, sheathed in protective mucus. Although the adults don’t care for the eggs, some species will cover them with defensive chemicals to deter predators. This Hypselodoris nudibranch must have just finished laying her eggs.