Answers will be posted in on the door of PR-110 The Porifera are commonly called sponges, and they are multicellular animals. Their organization is at the cellular level as they lack any type of tissue. There are approximately 5,000 species of sponges and they are frequent inhabitants of marine communities with a few of them living in freshwater. As part of the aquatic communities, sponges provide shelter and habitats for many smaller organisms and food for a few. The body shape of sponges varies from simple to infolded or multichambered.
Water flows into the sponge body by way of pores all over the external surface.
After passing through the body cavity, the water exits through the osculum or opening at the top of the sponge. In colonial forms, several sponges may share a common osculum. They feed by using flagellated choanocytes while the water flowing past also exchanges gases. The body of the sponge is supported by spicules made of collagen, spongin, calcareous, or siliceous spicules. Sometimes there are combinations of spicule types.