Nudibranchs (commonly referred to as sea slugs) are many divers’ favourite invertebrates. They’re typically small and brightly coloured (indicating their unpleasant taste to would-be predators) and are thus understandably appealing. But this little snippet is all about how they produce their next generation.

Nudibranchs are hermaphrodites; that is, each individual possesses both male and female sex organs. When they meet and decide to mate, they arrange themselves head to foot so they can exchange sperm. They will then separate and each will find somewhere suitable (usually a hard surface) to lay their eggs. The eggs are fertilized as they emerge and are laid as a ribbon whose form and colour are characteristic of that species. Nudibranchs are also quite specific about what they eat, so always note their prey organism if you can, often a species of hydroid or bryozoan, which may assist in identifying the nudibranch.