Poriferans are known today as sponges. Fossil sponges come from the same time as the oldest fossils.There a re about 5000 species of sponges, with three distinct groups. The groups are hexactinellida (the glass sponges), the demospongia (the larges sponges), and the calcarea (the calcareous sponges). They all have the same circulatory system.
Calcarea
Sponges have flagellated cells over the surface of their bodies, these are cells that have tails that wiggles. The collective effort of all these cells creates a water current through the many porous openings in the sponges body. Because of this, they are able to live without a circulatory system. However it can be seen as a water based circulatory system.The water current also delivers a constant supply of oxygen to the sponge and removes nitrogenous waste products. Water exits the sponge through the large opening at the top of the body called the osculum.
Demospongiae
Sponges have flagellated cells over the surface of their bodies, these are cells that have tails that wiggles. The collective effort of all these cells creates a water current through the many porous openings in the sponges body. Because of this, they are able to live without a circulatory system. However it can be seen as a water based circulatory system.The water current also delivers a constant supply of oxygen to the sponge and removes nitrogenous waste products. Water exits the sponge through the large opening at the top of the body called the osculum.
Hexactinellid
Sponges have flagellated cells over the surface of their bodies, these are cells that have tails that wiggles. The collective effort of all these cells creates a water current through the many porous openings in the sponges body. Because of this, they are able to live without a circulatory system. However it can be seen as a water based circulatory system.The water current also delivers a constant supply of oxygen to the sponge and removes nitrogenous waste products. Water exits the sponge through the large opening at the top of the body called the osculum.