Answer:
By feeding on the organism at lower trophic level with in any ecosystem
Step-by-step explanation:
In any trophic level, the organism at higher level feed upon the lower level organism to get energy for themselves.
Usually in an ecosystem when an organism feed upon other organism they get only 10% of their total energy because remaining 90% of energy is preserved by themselves to carry out metabolic processes with in them.
In this way energy is transfered from producers (chlorophyll containing organisms) to the primary consumer, then to secondary , tertiary consumers and lastly to the decompose rs.