The marine environment of South Australia is home to many species of invertebrates. Invertebrates are animals that lack backbones, and here we explore species that live in the ocean around South Australia.
Sponges are the oldest group of animals, and have a simple body plan compared to most other animals. They are found in all aquatic environments, including the deep sea. Most sponges attach to a hard surface, just like the ones in this image. These two species, Aplysilla rosea (above) and Aplysilla sulfurea (below), are attached to the jetty piles of the Point Turton jetty.
Jellyfish like this one, Pseudorhiza haeckeli, are in Phylum Cnidaria and related to other animals such as sea anemones and corals. All of these animals have stinging cells that produce nematocysts that can sting predators and prey – so be careful not to touch them!
Hermit crabs are a specialised group of crabs that use an empty shell as their home. They have a very soft abdomen, which would be very tasty for predators. To stay safe, the crabs carry the shell with them at all times, and only leave it when they outgrow it.
This isopod (Creniola laticauda) is parasitic, and feeds on the blood and body fluids of the leafy sea dragon (Phycodurus eques). It is also camouflaged, being very similar in colour and pattern to the host sea dragon. Can you see all of the isopods? Hint: there is one large female and four smaller males in this image.
Giant Australian Cuttlefish
The largest cuttlefish species in the world, Sepia apama is found around coasts of southern Australia. Breeding aggregations are formed once a year off Whyalla in SA, where many individuals come together to breed. These cuttlefish have special cells in their skin that allow them to change their appearance very quickly. One minute they are camouflaged by being similar in colour and texture to their surrounding environment, the next minute they are displaying various colours. Cuttlefish also have a cuttlebone, that, when the cuttlefish die, are found washed up on the beach, a common sight in South Australia.
Fan worms are related to the land-based earthworms! However, fan worms, including this one, Sabellastarte australiensis, are found in the oceans and build their own tubes to live in. They have a large crown of feathery tentacles they use for feeding.
South Australia is home to many amazing marine invertebrates, including this basket star (Conocladus australis) which is sitting on a soft coral (Mopsella sp.). If you want to learn more about the Marine Invertebrates of South Australia, check out the book “A field guide to the marine invertebrates of South Australia” by Karen Gowlett-Holmes, available at the South Australian Museum gift shop and visit our Biodiversity Gallery’s marine area.
Australian and international scientists rely on the Marine Invertebrates Collection at the Museum as a critical source of material for research. Identifying new species of invertebrates, tracking how and where they live, and learning about their rates of change and extinction can give scientists important insights into diversity, evolution, and changing world climates and habitats.