Deep Sponge Gardens

In the deeper (25+m) waters along the Great Southern Reef, Sponges compete for space and nutrients. While sponges are found at virtually all depths, they tend not dominate shallow sites as the faster-growing seaweeds thrive and outgrow other organisms. As the most primitive of all multicellular animals, rather than having organs, their body is made up of a fibrous protein and hard, pointed internal skeletons called spicules made of calcium carbonate or silica.
These internal skeletons can determine the sponge’s shape. If water flow has been minimised, all known sponges are able to remold their bodies to another shape. Whatever their decided shape, it is adapted for the most efficient water flow through its central cavity where it receives its nutrients. It is currently estimated that Australia possesses a little over 1400 described species of sponges with many found along the Great Southern Reef and at least half of these thought to occur nowhere else in the world.