Answer:
Through different studies scientist have quantified the amount of energy that moves to the next trophic level. Most of the energy is used for metabolic processes and released as heat to the environment.
The amount of energy left for the next level is around 10%, if a herbivore takes 1,OOO Kilojoules the energy left for the next level would be around 100 Kilojoules, this explains why you cannot find a food chain with more than 7-8 levels (ocean) on land is usually between 4-6 levels.