SEA SLUGS Nudibranchs have naked gills at the rear.

Opisthobranchs means gills at the rear. They include Umbrella shells, Bubble Shells, Sea Hares and Nudibranchs. Umbrella shells and Bubble shells have a reduced shell . Sea Hares have a rudimentary shell inside their mantle. Sea Slugs only have a shell for one day in the larval stage which is then lost.


Recent research is making many more fascinating discoveries about Nudis. All of them are hermaphrodites. Many are brightly coloured to advertise the fact that they are toxic. Some have camouflage that is so good that they are virtually invisible. Some can shed their mantle or cerrata to escape predation.

Short Tail Ceratosoma Roboastra Polycera
flabellina siboga Verco's Tambja

Names from the top.

The yellow form of the Short Tail Ceratosoma, resting on a brown algae called Ecklonia.

The Bicolour Flabellina has many cerrata which function as gills. Fiji

An unusual Roboastra from Kandavu, Fiji.

The Aeolid Cuthona siboga feeds on Hydroids . It stores the stinging cells in the orange tips of its cerrata. It has pink symbiotic algae growing within its flesh just under the zone of cerrata.

The Polycera has seven oral tentacles. Sydney

Vercoe's Tambja, Shiprock, Sydney. They feed on Blue bryozoans exclusively.