Shells
Shells are present during the larval stage but are shed; adults are shell-less.
Nudibranch
Nudibranchs are soft-bodied marine gastropods known for bright colours and striking forms, comprising about 3,000 described species.
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Last Updated Mar 9, 2026 ·
Species Guide
What to know about nudibranches
A clean field guide focused on habitat, identification, behavior, and conservation context without burying the useful parts.
Nudibranchs are a group of soft-bodied marine gastropod molluscs in the order Nudibranchia that lose their shells after the larval stage. They are noted for often extraordinary colours and striking body forms and have earned colourful common nicknames such as "clown", "marigold", "splendid", "dancer", "dragon" and "sea rabbit". The name 'nudibranch' derives from Latin nudus (naked) and Ancient Greek bránkhia (gills). Although commonly called sea slugs, nudibranchs are one group within the broader assemblage of sea slugs; several other unrelated sea slug groups can look similar and are sometimes confused with nudibranchs.
The strongest linked planning options currently surface around destinations such as Cape Town, Costa Brava and Medes Islands, Togean Islands and Tomini Coast and countries such as Spain, Indonesia, Japan for divers building trips around nudibranches.
Identification
How to identify nudibranches
The visual markers divers can use underwater, plus the species most likely to cause confusion.
Key identification markers
Body type
Soft-bodied marine gastropod molluscs.
