Producers are autotrophs that manufacture their food from inorganic raw materials with solar energy absorbed by chlorophyll. The process is called photosynthesis. Photosynthesis is performed by green plants, algae, phytoplankton, blue-green algae, and some bacteria. Two processes in photosynthesis are the conversion of solar energy into chemical energy and organic food formation. Autotrophs are called producers because they manufacture food not only for themselves but for all other living beings or heterotrophs.

Herbivores are first-order or primary consumers, which directly feed on plants and their seeds or fruits. They have special enzymes to digest the cellulose of plants. Examples: cow, buffalo, goat, sheep, horse, camel, deer, rabbit, squirrel, grasshopper, etc. Herbivores of the aquatic ecosystem are small fish, molluscs and zooplankton.

Carnivores are animals that feed on other animals. Primary carnivores or second-order consumers feed on herbivores. Example: frog, jackal, fox, wildcat, some fishes, birds and snakes. Secondary carnivores or third-order consumers prey upon primary carnivores. Example: peacock, snake feeding on a frog. Top carnivores are those carnivores that are not preyed upon by other animals. Example: tiger, lion, shark, eagle.