Sponges

An unidentified species of Sponge ( Photo: Maunoa Karo)

Sponges are aquatic animals which mostly found in marine waters, though some of them inhabit freshwater lakes. The sponges come under the phylum porifera. Their form can resemble barrels, volcanic mounds, baskets, or encrusting sheets.
The sponges do not have muscles, nerves, mouths or body organs and their bodies are delicate and filled with a soft substance known as mesohyl, resembling jellies. Being aquatic creatures, their body allows them to absorb fluids, water, oxygen and food, with ease.

An interesting thing to note about sponges is that they don't have a digestive, circulatory or nervous system. They extract the food out of the water entering their body through pores. Since sponges need some kind of a substrate, such as rocks to remain stable in the sea, they are sessile - sedentary organisms. There are more than 7000 sponge species and possibly more of them would be discovered in the future. The different forms of sponges are encrusting-sheets, mounds, tubes and upright-sheets.

Sponges primarily feed on bacteria, but in some cases microbes live inside their bodies as endosymbiont - an organism living in symbiosis with its host, and inside its body. Some sponges have also turned into carnivores, where the food availability is scarce.



Spheciospongia vagabunda commonly found in shallow waters, in seagrass beds or sand.