Porifera (phylum) en

Phylum of primitive multicellular aquatic animals. There are approximately 5,000 described species and inhabit all seas, where they occur attached to surfaces from the intertidal zone to depths of 29,000 feet or more. Early naturalists regarded the sponges as plants because of their frequent branching form and their lack of obvious movement. The animal nature of sponges was first described in 1755, and was confirmed in 1765 after observations revealed movement of their openings. In structure, function, and development, however, sponges are distinct from other animals. Many zoologists regard sponges as occupying an isolated position in the animal kingdom and classify them in the subkingdom Parazoa. Other sources consider sponges relatives of the invertebrate animal group coelenterates. Aquatic, chiefly marine animals of the phylum Porifera, varying greatly in size, shape, and color, and having a porous body and siliceous or calcareous internal framework, living permanently attached singly or in groups, feeding b filtering food particles from the water that enters their internal body channels through their pores. They are very simply organized with no mouth, digestive cavity, nerves, muscle, or true behavior, and sometimes are considered to be colonized protozoans rather than single multicellular organisms. For the light, porous, yielding fibrous skeletal matter of these animals, use "sponge (material)."