About 10 percent of the energy in one trophic level is transferred to the next level in a food chain.

What this 10% means

  • If plants capture 10,000 units of energy from the Sun, only about 1,000 units become herbivore biomass, and only about 100 units become primary carnivore biomass.
  • The other roughly 90 percent at each step is lost as heat, movement, respiration, and waste, so it is no longer available to the next trophic level.

Why only a small amount is passed on

  • Organisms use most of the energy they take in for staying alive: breathing, moving, keeping body temperature stable, and maintaining cells.
  • Some parts of food are not digested or are excreted, so that energy never becomes part of the consumer’s biomass.
  • Because of these losses, energy decreases sharply as you go up the food chain, which limits ecosystems to only a few trophic levels (often around four to six at most).

Simple example

Imagine a grassland:

  1. Producers (grass): 10,000 kilocalories of energy.
  1. Primary consumers (insects, herbivores): about 1,000 kilocalories (≈10%).
  1. Secondary consumers (small predators): about 100 kilocalories.
  2. Tertiary consumers (top predators): about 10 kilocalories.

At each step, only around 10% of the energy moves up to the next trophic level, which is why energy pyramids get very narrow toward the top.

Information gathered from public forums or data available on the internet and portrayed here.