Extracellular digestion is a process in which saprobionts feed by secreting enzymes through the cell membrane onto the food. The enzymes catalyze the digestion of the food into molecules small enough to be taken up by passive diffusion, transport or phagocytosis . Since digestion occurs outside the cell, it is said to be extracellular. It takes place either in the lumen of the digestive system, in a gastric cavity or other digestive organ, or completely outside the body.