Even more remarkably, the disassociated cells will survive. Even more remarkably, the disassociated cells can reassemble as a functioning organism. Structure of Sponges Sponge walls filter seawater and remove food particles. This wall is lined on the outside with an epithelial layer of flat cells. Folds of the wall form incurrent canals opening to the outside and flagellated canals opening to the central chamber called the spongocoel.
Collar cells produce a constant flow of water into the sponge.
Water enters incurrent canals and flows through pores within porocytes, into the flagellated canals, and on to the spongocoel. Eventually the filtered water exits through a large hole in the end of the sponge called the osculum. Choanocytes remove suspended food particles as water moves through the sponge. A specialized collar of microvilli surrounding flagella of the choanocytes traps food particles that are engulfed by the cell body. Digestion is intracellular, meaning that it occurs inside cells.