AI Tutor
If you hike through a forest, you will see millions of green leaves, thousands of insects, but maybe only a single hawk soaring overhead. Why can an ecosystem never support a million hawks in that same forest?
The answer lies in how energy moves through living systems, where living things lose the vast majority of their chemical fuel before anyone can eat them.

Trophic Levels and the 10% Rule

A trophic level is an organism's feeding step in an ecosystem, starting with primary producers like plants and climbing up to apex carnivores.
In 1942, ecologist Raymond Lindeman measured energy movement in a Minnesota lake and formulated the Ten Percent Law: on average, only about 10% of the energy stored as biomass in one trophic level is passed to the next.
Where does that missing 90% of energy actually go if it never reaches the predator?

Why Energy Dissipates: Metabolic Heat

Energy cannot be destroyed—the First Law of Thermodynamics proves that total energy in a closed system is always conserved.
Instead, as organisms break down glucose during cellular respiration to power movement, growth, and body warmth, most of that energy converts into disordered metabolic heat that radiates away into the environment.
Along with metabolic heat, some biomass simply goes unconsumed (such as wood or bones) or is eliminated as undigested waste (feces), leaving only a tiny fraction stored as edible tissue.
How do we calculate the exact energy available to top predators in a real ecosystem?