The soft-bodied marine gastropod molluscs known as nudibranchs are some of the most beautiful – and almost the most bizarre – of sea creatures. The name (pronounced ‘nudibrank’) means ‘naked gills’, as they shed their shells after the larval stage.
They belong to the subclass Ophistobranchia, or sea slugs.
There are perhaps 3000 species of nudibranch found mainly on ocean floors around the world.
The species shown above, Phyllodesmium serrata, grows to 3 or 4 centimetres in length and lives in rocky reef areas off Japan and the south-eastern coasts of Australia.