Food chains

A food chain shows what eats what in a particular habitat. It shows the flow of energy and materials from one organism to the next, beginning with a producer.

In the example, 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.

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

A food chain

The Sun is the ultimate source of energy for most communities of living things. Green plants are usually the producers in a food chain.

Producers are organisms that make their own organic nutrients (food) - usually using energy from sunlight. Green plants make their food by photosynthesis. The other organisms in a food chain are consumers, because they all get their energy by consuming other organisms.

Organism How it gets its energy
Consumer Feeding on other organisms
Primary consumer Eating plants
Secondary consumer Eating primary consumers
Tertiary consumer Eating secondary consumers
Herbivore Eating plants
Carnivore Eating other animals
Decomposer Feeding on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces
Glossary
  1. biomass The dry mass of an organism.
  2. decomposer An organism which eats dead organisms or animal droppings, and breaks them down into simple materials.
  3. dry mass The mass of an organism after its water has been removed.
  4. ecosystem A community of animals, plants and microorganisms, together with the habitat where they live.
  5. food chain A sequence (usually shown as a diagram) of feeding relationships between organisms, showing who eats what and the movement of energy through trophic levels.
  6. food web Diagram of feeding relationships between organisms in an evnironment.
  7. habitat Place where plants, animals and microorganisms live.
  8. photosynthesis A chemical process used by plants and algae to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis.
  9. primary consumer The name given to an organism that eats a producer. A herbivore.
  10. producer A green plant that makes its own food by photosynthesis.
  11. secondary consumer An organism that obtains its energy by eating the primary consumer.
  12. tertiary consumer An organism that obtains its energy by eating the secondary consumer.
  13. trophic level The position of an organism in a food chain, food web or pyramid.
  14. valid A measurement, test or observation that can be repeated or reproduced to get similar data to support a conclusion.