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