Sea slug

Sea slug is a common name for a diverse group of marine gastropod molluscs, most of which have lost or reduced their shells.

Sea slug is a common name for a diverse group of marine gastropod molluscs, most of which have lost or reduced their shells. The term is used broadly and can include nudibranchs as well as other shell-less or nearly shell-less sea snails such as sea hares. Sea slugs occur in oceans worldwide and are known for their varied forms, colours, and ecological roles.

Classification

Sea slug is a broad common name used for several groups of marine gastropods in the phylum Mollusca and class Gastropoda. It does not refer to a single evolutionary lineage, and its use may vary by source.

Physical characteristics

Sea slugs are soft-bodied and often shell-less or nearly shell-less. Many species have vivid colours, external gill structures, cerata, or rhinophores, features that help with breathing or sensing their environment.

Habitat and distribution

Sea slugs live in marine environments around the world. They are commonly reported from shallow coastal areas, coral reefs, seagrass beds, kelp forests, and some deeper-sea habitats.

Ecology and behaviour

Different sea slugs have varied diets and life histories, including feeding on algae, sponges, anemones, or other small marine animals. Some species are known for chemical defences, while others can incorporate compounds from their prey.