Understand that energy flows in one direction through ecosystems and is NOT recycled.
Observe the 10% Rule: only ~10% of energy is transferred from one trophic level to the next.
Explain why ecosystems rarely support food chains longer than 4 or 5 levels.
Where does the 90% go?
When a rabbit eats grass, 90% of the energy is "lost" to the environment as low-quality heat (Cellular Respiration), movement, and undigested waste. Only 10% is converted into new rabbit biomass.
Tags
APES10% RuleThermodynamicsTrophic Pyramid
Joules (J) of Available Energy
Solar Energy Input1,000,000 J
Tertiary Consumer Energy10 L
Primary Producers (Plants) 100,000 J
Energy Transfer Efficiency 10%
Notice: The pyramid shape demonstrates the Second Law of Thermodynamics (Entropy). You need an absolute massive base of plants to eventually support a single apex predator like a hawk or lion.
Quick Quiz
Why is it ecologically much more efficient for humans to eat a plant-based diet rather than an exclusively meat-based diet?