(1) Producers: Organisms that can manufacture their own food are called producers. For example, green plants make their own food by photosynthesis.
(2) Consumers: Organisms that cannot prepare their own food but consume food pepared by green plants are consumers. They also obtain their food by eating other living or dead animals.
Types of Consumers :
(a) Primary Consumers or Herbivores. Animals that get their food directly from plants are Herbivores, e.g. cow, dear, goat etc.
(b) Secondary Consumers or Carnivores. They eat primary consumers, e.g. snakes, frog, lizard.
(c) Tertiary Consumers. They eat secondary consumers, e.g. lion, tiger, leopards etc.
(3) Decomposers: The microorganisms which fed on the dead bodies of plants and animals and break them into simple substances are caled Decomposers, e.g. Bacteria and fungi.