A spongocoel (), also called paragaster (or paragastric cavity), is the large, central cavity of

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), 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 t ...

s. Water enters the spongocoel through hundreds of tiny pores ( ostia) and exits through the larger opening (

osculum The osculum (plural "oscula") is an excretory structure in the living sponge, a large opening to the outside through which the current of water exits after passing through the spongocoel. Wastes diffuse into the water and the water is pumped thr ...

). Depending on the body plan of the sponge (which can be

asconoid Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), 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 t ...

, syconoid, or leuconoid), the spongocoel could be a simple interior space of the sponge or a complexly branched inner structure. Regardless of body plan or class, the spongocoel is lined with

choanocyte Choanocytes (also known as "collar cells") are cells that line the interior of asconoid, syconoid and leuconoid body types of sponges that contain a central flagellum, or ''cilium,'' surrounded by a collar of microvilli which are connected by a th ...

s, which have

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

that push water through the spongocoel, creating a current. The spongocoel is lined by a variety of cell types, each having a unique function: *

porocyte Porocytes are tubular cells which make up the pores of a sponge known as ostia. Description Covering the sponge is a layer of cells known as the pinacoderm, which is composed of pinacocytes. In a sponge, pinacocytes are a thin, elastic layer which ...

s – line the pores of the sponge and are the structure through which water is taken into the organism * choanocytes – exhibit flagella that create inward currents of water for the sponge's stationary filter feeding mechanism *

amoebocytes An amebocyte or amoebocyte () is a mobile cell (moving like an amoeba) in the body of invertebrates including cnidaria, echinoderms, molluscs, tunicates, sponges and some chelicerates. They move by pseudopodia. Similarly to some of the white blood c ...

– motile cells that perform various digestive functions within the sponge by transporting and/or storing food and excreting waste.

References

Sponge anatomy {{Animal-anatomy-stub