What happens to energy as it is passed up a food chain?

As energy is transferred up a food chain, it undergoes a significant reduction primarily due to the laws of thermodynamics, specifically the second law, which states that energy transformations are not 100% efficient. During each transference—from producers to herbivores to carnivores—much of the energy is converted into heat and lost to the environment due to metabolic processes such as respiration, movement, and growth.

This loss of energy in the form of heat explains why energy decreases at each trophic level, typically allowing only about 10% of the energy at one level to be available to the next level. For example, if plants capture energy from the sun through photosynthesis and then are eaten by herbivores, a considerable amount of that energy is released as heat when the herbivores metabolize the food. This concept is a fundamental part of understanding ecosystem efficiency and energy flow, often illustrated through energy pyramids in ecological studies.