Why is there a limit to the number of links in a food chain?

1 Answer
Feb 3, 2017

In an ecosystem biotic organisms form a food chain due to their feeding habit. All heterotrophic organisms are directly or indirectly drawing energy from autotrophic green plants.

The energy that flows along the food chain is actually trapped solar energy, which is converted into chemical energy by plants. This is why plants are regarded as producers in an ecosystem.

When all biotic organisms of food chain are represented on different trophic levels we would realise that the number of trophic levels in an ecosystem could be limited to four, rarely five.

This is because only 10% of the energy from producers get transferred to the level of primary consumers; likewise only 10% of the energy fixed as animal flesh can be transferred to the secondary consumers. Thus very little energy could be actually available for top consumers at the end of the food chain. Limited number of trophic levels means limited number of links in food chain.

(Please note that an ecosystem becomes sustainable when several food chains remain interconnected and form a food web, though organisms could be part of only four trophic levels.)

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