Which of the following always has a pyramidal shape, that is, decreasing values at higher trophic levels?

Pyramid of energy

The pyramid of energy is always upright and can never be inverted. This is because as energy flows from one trophic level to the next, some amount of energy is always lost as heat through various metabolic processes and ecological inefficiencies.

Each bar in the energy pyramid represents the amount of energy present at each trophic level in a given time or annually per unit area. The bars in the energy pyramid become progressively smaller as you move up the trophic levels, indicating the decreasing amount of available energy.

The loss of energy as heat at each trophic transfer is a fundamental principle of thermodynamics, specifically the second law of thermodynamics. This law states that energy transformations are not 100% efficient, and some energy is always dissipated as heat in any energy transfer process.

Therefore, due to the unavoidable loss of energy as heat at each step, the pyramid of energy remains upright, with a decreasing amount of energy available at higher trophic levels.