Nudibranchs or sea slugs are a type of marine gastropod mollusc. They come in a diverse array of forms with often bright colors and markings that help to demonstrate their toxic nature to predators.
Nudibranchs are hermaphrodite, meaning each individual has both male and female sex organs, but they cannot fertilize themselves.
Mating pairs swap sperm sacs via a copulatory tube, and mating can last from a few seconds to a whole day, depending on the species.
In many species, each slug then lays eggs in one to six ribbon-like masses, attached to the substrate in an anti-clockwise spiral. In other species, the eggs may be laid as capsules inside a cylindrical cord or a small kidney-shaped sac.
The spawn are protected from predators via chemical defense, and the parents play no part in raising the larvae.
Matthew Oldfield is a freelance photographer based in Bali, Indonesia, specializing in editorial and documentary images from both above and below the waves. He works primarily with charities, NGO’s, and other organizations working to conserve the environment, endangered species, and disappearing cultures.
Matthew is on Twitter @matthewophoto. More of his photos can be found at matthew-oldfield-photography.com
