SUMMARY
Energy flows through ecosystems in one direction.

A pyramid of biomass shows the total biomass, or total amount of living material, at each trophic level. Every trophic level loses most of its energy to the environment as heat, which becomes unavailable to the next trophic level. Therefore, biomass decreases with each trophic level.

A pyramid of energy shows the flow of energy from one trophic level to the next. It has a large base (primary producers) and progressively smaller areas for each subsequent trophic level, much like a pyramid of biomass. Loss of energy (heat) and biomass reduction from one trophic level to another vary widely, and may approach 90%.

Because of the amount of energy lost on the way up the chain, an ecosystem can support only a few top predators. Ecosystems have fewer secondary consumers than primary, and even fewer tertiary consumers (carnivores), because organisms lose energy at each trophic level.

Activity
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