Sponges have bodies that consist of jelly-like mesohyl (the gelatinous matrix within a sponge) sandwiched between two thin layers of cells with an endoskeleton and branching water intake canals lined by flagellated collar cells for feeding and excretion.

Water passes through these animals by way of the canals and a series of flagellated chambers (lash-like appendages used for locomotion) and exits via large channels and pores or oscula.