Porifera

noun

The sponges. Non-mobile animals consisting of many cells but built on a different plan from the Metazoa and are hence grouped separately. They have no nervous system and posses collar cells (choanocytes). Currents of water are drawn into the body through small pores (ostia) and passed out through larger pores (oscula), food particles being collected in the process. In most sponges the body is supported by a skeleton of calcium carbonate, silica or spongin.

Multicellular organisms containing a system of chambers and passageways that allow water to circulate constantly through the body. In many species, body size and shape is highly variable. Many sponges have a skeleton consisting of either calcium carbonate, silicon dioxide, or collagen fibers, or a combination of these substances. Sponges can reproduce sexually or asexually. In sexual reproduction, a larva called a parenchymula often develops in the sponge and swims out to live freely for a day or two before settling to the substrate. Sponges are suspension feeders, creating currents that draw in plankton and organic detritus from the water column.