Question

Why is the pyramid of energy never inverted? Explain.

Hint:

Recall the 10 percent law and where the missing 90 percent of energy actually goes.

Answer 1

Step 1: Understanding the Concept:
A pyramid of energy plots the rate of energy flow (energy per unit area per unit time) through each trophic level, from producers up to top consumers, unlike a biomass pyramid which just measures mass at one instant.

Step 2: Key rule that governs it.
Energy transfer between trophic levels obeys the second law of thermodynamics: whenever energy is transformed (for example, food eaten and used for movement, growth, or heat), some of it is always lost as heat, so the amount passed on is always less than what was received.

Step 3: Apply this level by level.
Only about 10 percent of the energy at one trophic level is typically available to the next level (the 10 percent law); the rest is used up in respiration or lost as heat. This means every higher trophic level must receive less energy than the one below it, with no exceptions.

Final Answer:
Because energy is always lost as heat at each transfer, and flow is one directional, energy at a level can never exceed the level below it, so the energy pyramid is always upright, never inverted.