Southern Australian TEMPERATE REEFS MOBILE INVERTEBRATES Mobile invertebrates are those animals without backbones that move about such as urchins, sea stars, crabs, prawns, lobsters, snails, squid and cuttlefish. This fact sheet covers molluscs and worms. See Mobile Invertebrate Fact Sheet 1 for crustaceans and echinderms

David Muirhead Cypraea friendii

Vicki Billings Nudibranch showing gills Reef Watch Reef Watch South Australia FACT SHEET 2 FACT

Molluscs – snails, slugs, bivalves, squid, Nudibranchs (sea slugs) are favourites of divers octopus, cuttlefish and more and underwater photographers as they are often These are soft-bodied animals with most having a hard incredibly colourful and may have beautiful shell. The majority have a head and a foot, eyes and ornamentation called cerrata on their backs. internal organs such as kidneys, gonads, heart, gills Their bright colouration is thought to be a warning and a nervous system. The molluscs include a wide to predators. variety of animals such as chitons, snails, nudibranchs, The word ‘nudibranch’ refers to naked gills that limpets, bivalves, cuttlefish, squid and octopus. are on the back of sea slugs. These are incredibly vulnerable to being nipped by predators, so most sea slugs are able to retract their gills into their body when threatened. Bivalves are all those molluscs with two shells such as cockles, mussels, oysters, scallops and razor shells. Most bivalves are filter feeders, siphoning

water through their bodies to filter out plankton to eat.

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Adrian Browm Octopus maorum

David Muirhead Giant Australiancuttlefish

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