The amount of energy flow in an ecosystem decreases with successive tropic levels as only 10% of energy gets transferred from one trophic level to next successive level. The energy lasts in the form of respiration and other important activities for maintaining life. If more trophic levels are present, the residual energy will be limited and decreases to such an extend that it cannot further support any trophic level by the energy flow. Thus, it is rightly said that the food chain is generally limited to the 3-4 trophic levels only.
For example,
