Sponges, the members of the phylum Porifera (/pəˈrɪfərə/; meaning 'pore bearer'). They are a basal animal clade as a sister of the Diploblasts.
They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them. Sponges have unspecialized cells that can give rise to other types of cells. Since sponges do not have nervous, digestive or circulatory systems, so they mostly rely on maintaining constant water flow through their bodies to obtain food and oxygen and to remove wastes. The approximately 5,000 living sponge species are classified in the phylum Porifera, which is composed of three distinct groups, the Hexactinellida (glass sponges), the Demospongia, and the Calcarea (calcareous sponges).
Poriferans or sponges don't have mouths; instead, they have tiny pores in their outer walls through which water is drawn. Cells in the sponge walls filter goodies from the water as the water is pumped through the body and out other larger openings. The flow of water through the sponge is unidirectional, driven by the beating of flagella which line the surface of chambers connected by a series of canals.