Animals derive organic food materials by consuming products of plants - Heterotrophic nutrition.
Types of Heterotrophic Nutrition
(i) Holozoic - When whole plants or their parts and whole animals or their parts or both are consumed by mouth, e.g., most of the animals.
(ii) Saprobiotic - When decaying organic materials of plant or animal origin are consumed e.g., fungi, bacteria, some protozoans.
(iii) Parasitic - When a living organism feeds on another living organism and causes harm e.g., tape warm, malarial parasite etc.