Phylum Porifera (1st Phylum)

The Phylum Porifera contains the sponges. There are approximately 6000 sponges. Most live attached to marine reefs. Approximately 100 species live in freshwater. They lack true tissue and organs and therefore the cells are relatively unspecialised. Sponges often have complex life histories. Some species are free standing whilst others form an encrusting layer over rocks.
Sponges are filter feeders. The surface of the sponge has many pores (ostia) through which water is drawn into the body. The water is drawn into a series of canals and chambers where food particles (plankton) are trapped. The water then passes out of the body through larger pores (oscules). A sponge can pump hundreds of litres through it's body each day.
Being filter feeders, sponges live most successfully in areas with strong currents or wave action. They grow less rapidly than seaweeds, therefore are less common in shallow sunny reefs.
A few specialised opisthobranchs (sea slugs), crustaceans, echinoderms and fish are known to feed on sponges.
Most carnivorous animals avoid sponges because of the splinter-like spicules and toxic chemicals produced by the sponge.
SPONGES AT THE MDC
The following species of sponge are found at the Marine Discovery Centre:

 Tethya sp. ? - Pumpkin sponge

Tethya sp. ? - Pumpkin Sponge Picture: MDC

Habitat: Reef, sand, muddy bottom; 2 - 15 m depth Distribution: Unknown due to lack of taxonomic resolution Maximum size: Up to approximately 300 mm diameter Diet: Plankton (filter feeder) Comments:  Staff at the Marine Discovery Centre find Pumpkin Sponges commonly in the D'Entrecasteaux Channel, often hauling them up with the dredge. Sponges often form what's called a "Sponge Garden" where large numbers of sponges can be found.

Carteriospongia caliciformis - Plate Sponge

Carteriospongia caliciformis - Plate Sponge Picture: MDC

Habitat: Moderately exposed reef, 5 - 35 m depth Distribution: SA to Victoria and around Tasmania Maximum size: Up to approximately 300 mm diameter Diet: Plankton (filter feeder) Comments:  This species lacks spicules and only has spongin for support. It occurs commonly on deeper reefs in areas of high current flow. The irregular green colour of the sponge may be caused by green symbiotic algae growing on the surface.

Dendrilla rosea - Rosea Sponge

Dendrilla rosea - Rosea Sponge Picture: MDC

Habitat: Moderately exposed reef, 3 - 22 m depth Distribution: SA to NSW and around Tasmania Maximum Size: Length to 400 mm Diet: Plankton (filter feeder) Comments:  Bright pink sponge with deeply ruffled surface. Can be erect or encrusting.

Siphonochalina sp. ? - Finger Sponge

Siphonochalina sp. ? - Finger Sponge Picture: MDC

Habitat: Exposed reef, 20 - 35 m depth Distribution: Eastern Tasmania Maximum size: Length to 150 mm Diet: Plankton (filter feeder) Comments:  This species has long tubular extensions (fingers!). Common on deep Tasmanian reefs.