8. Our Environment
Food chain is a sequence of organisms in a biotic community through which food passes with members of a step becoming food of the members of the next step of the sequence. In other words, it is a list of who eats whom in a biotic community. A food chain usually consists of producers, various levels of consumers and decomposers. Each step or division in food chain which is characterized by a particular method of obtaining food is called trophic level.
They constitute the base or beginning of a food chain. They constitute the first trophic level (T1) of a food chain.
Herbivores or first order consumers (Primary consumers) :
They are animals which feed on plants or plant products. e.g., Grasshopper, Rabbit, Deer Elephant. Herbivores constitute second trophic level (T2).
First order (Primary) carnivores or second order consumers (secondary consumers) :
They are animals which prey upon herbivores, e.g., Frog, Wild Cat, Fox. These animals form the third trophic level (T3).