Nudibranch

Nudibranchs () are a group of soft-bodiedmarinegastropodmolluscs, belonging to the orderNudibranchia, that shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to match, such as "clown", "marigold", "splendid", "dancer", "dragon", and "sea rabbit". About 3,000 species of nudibranchs are known.

The word nudibranch comes from the Latin 'naked' and the Ancient Greek (bránkhia) 'gills'.

Nudibranchs are often casually called sea slugs, as they are a family of opisthobranchs (sea slugs), within the phylum Mollusca (molluscs), but many sea slugs belong to several taxonomic groups that are not closely related to nudibranchs. A number of these other sea slugs, such as the photosyntheticSacoglossa and the colourful Aglajidae, are often confused with nudibranchs.