Hint: Organisms that depend directly on produced food are primary consumers and organisms that depend on primary consumers are secondary consumers. Secondary consumers can also directly depend on products.
There are four trophic levels in an ecosystem namely the first trophic level, second trophic level, third trophic level, fourth trophic level. Organisms in these trophic levels are producers, primary consumers, secondary consumers, tertiary consumers respectively. More than one trophic level is occupied by given species in an ecosystem. For example, consider a sparrow. It acts as a primary consumer when it eats seeds and fruits. It acts as a secondary consumer when it eats ants and other insects.
- Energy flows into the biological system i.e, the ecosystem from the sun.
- Several food levels are included in the environment of biological systems called trophic levels.
- A trophic level is composed of those organisms which have the same source of energy and having the same number of steps (energy storing and transfer steps) away from the sun
- Thus, plants and other producers belong to the first trophic level and herbivores belong to the second trophic level, carnivores occupy the third trophic level. Carnivores belong to the third trophic level and fourth trophic level occupy the fourth and fifth trophic level respectively.
Note: -In an ecosystem, the three main food chains found are the grazing food chain, parasitic food chain, and detritus food chain. According to Some authors, the parasitic food chain is also included in the grazing food chain.
-The food chain in an ecosystem ends with decomposers.