tHE Porifera pHYLUM
Porifera are commonly known as sponges. Early in the evolutionary time table, sponges may have been separated from other metazoans, (animals that have differentiated cells such as tissues and organs) and as a result have traveled their own evolutionary route up to present day. There are approximately 5,000 living species of sponges that have been discovered by scientists. A sponge is basically a water-filtering system. The sponges are immobile and feed on food particles in the water. All poriferans have a canal system which they pump water through. Water enters through pores in their outer layer called ostia, then flows through the canal system into another chamber called a spongocoel, and then exits through the oscula, or large opening in their cavity. Sponges have no specialized reproductive, digestive, respiratory, sensory, or excretory organs found in this group.