Spongocoel

A spongocoel (/ˈspɒŋɡoʊˌsiːl/) is the large, central cavity of sponges. Water enters the spongocoel through hundreds of tiny pores (Ostia) and exits through the larger opening (osculum). Depending on the body plan of the sponge (which can be asconoid, 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 choanocytes, which have flagella that push water through the spongocoel, creating a current.