Trophic levels

A food chain shows the flow of energy and materials from one organism to the next in a habitat.

In this example of a food chain, grass seeds are eaten by voles and voles are eaten by barn owls:

A food chain showing grass seed eaten by a vole which in turn is eaten by an owl.A food chain

The arrows between each organism in the chain always point in the direction of energy flow from the food to the feeder.

The position of an organism in a food chain is its trophic level. In the example above:

  1. the producer (grass) is the first trophic level
  2. the primary consumer (vole) is the second trophic level
  3. the secondary consumer (barn owl) is the third trophic level

Food chains are rarely longer than around four trophic levels as energy is used up or lost at each level.


A vole gets its energy from eating grass but they also eat insects. This makes it both a primary and secondary consumer. Which of these three terms best describes a vole: carnivore, herbivore or omnivore?