How much energy typically moves up from each trophic level in an ecosystem?

In an ecosystem, energy transfer between trophic levels is typically inefficient. Approximately 10% of the energy from one trophic level is passed on to the next level. This is known as the 10% rule of energy transfer. The majority of energy, about 90%, is lost at each level due to metabolic processes such as respiration, movement, growth, and reproduction, or is dissipated as heat.

For example, when plants (producers) convert sunlight into energy through photosynthesis, they utilize a significant portion of that energy for their own growth and metabolic functions, leaving only a fraction to be transferred to herbivores (primary consumers) that eat them. Herbivores also use another percentage of energy for their own needs, passing on just a fraction to carnivores (secondary consumers) when they are consumed. This efficiency is vital for understanding the structure and dynamics of ecosystems, influencing everything from food chain length to population sizes at different trophic levels.