| Holophytic Nutrition | Phytoflagellates possessing Chloroplasts or Chromatophores synthesize their food by photosynthesis. Carbon Dioxide and Water act as raw materials and to enter a complex cycle of chemical reactions and produce Dextrose sugar. From Dextrose, Paramylum may be formed (especially in Euglenoid flagellates). |
| Holozoic Nutrition | All Sarcodina are Holozoic or Parasitic. Involves development of organelles for food capture, ingestion, digestion and egestion of indigestible residues. Ingestion by Phagocytosis: Circumvallation: Amoeba sends out Pseudopodia to surround the prey without touching it. Later Pseudopodia fuse at their tips and food vacuoles are formed which in engulfed as a whole. Invagination: Food article is sucked in upon contact with the Ectoplasm. Food particle sinks into the endoplasm. Heliozoans: Axopodia act as traps. Withdrawn inside after capture into the cytoplasm. Foraminiferans: Produce a delicate reticulopodia net with a granular mucoid film. Ciliates: Oral apparatus meant for food capturing is well developed. By beating of cilia of oral groove, food is taken into buccal cavity and then driven towards mouth. Digestion: Digested within food vacuoles, which keep on circulating in the endoplasm. Lysosomes fuse with the food vacuole to provide the enzymes. Reaction at first is acidic (proteins to dipeptides) and later alkaline (dipeptides to amino acids, hydrolysis of carbohydrates). Proteolytic and Glycolytic enzymes. Absorption: Digested food is diffused into endoplasm, where it is assimilated into protoplasm. Excess food may be stored as Glycogen, Paramylum, Lipids, Chromatoid bodies etc. Egestion: Expelled from the hind part of the body. Ciliates possess an anal opening (Cytopyge) for this purpose. |
| Pinocytosis | Ingestion of liquid food by invaginations through the surface of the body. Pinocytotic channels are formed at some parts of the body surface to enclose the fluid food from the surrounding medium. Lower ends of the channels are pinched off as food vacuoles, which circulate in the endoplasm. Pinocytosis is induced only by certain active substances in the surrounding medium. e.g. Amoeba, certain flagellates and ciliates. |
| Saprozoic | Absorption of food by osmosis, through the general surface of the body (Osmotrophy). Food is in the form of solution of dead organic matter. Dissolved food materials, upon which the saprozoic protozoans subsist are proteins and carbohydrates. e.g. Polytoma |
| Myxotrophic | Combination of more than one mode of nutrition. e.g. Holophytic protozoans obtain food by phagocytosis and pinocytosis; Euglena is photoautotrophic (in the presence of sunlight) as well as saprophytic (in the absence of sunlight). |
| Parasitism | Mechanisms are broadly similar to non-parasite protozoans. Trypanosoma: Feed by osmotrophy. Digested food particles can be ingested by phagotrophy. |