Sponges do not contain digestive system but obtain nutrients through the diffusion process. Porifera is the most commonly asymmetrical in nature but can also have radial symmetry. Porifera has no coelom.
Lacking a true digestive system, they depend on the intracellular digestive processes of their choanocytes for their energy intake. Gas exchange, circulation, and excretion occur by diffusion between the water and the cells.
