Producers are green plants which photosynthesise. They use light energy from the sun to convert carbon dioxide from the air and water from the soil into glucose and oxygen. The glucose made can be eaten by other organisms so that they can use it for respiration which releases the energy stored in the glucose. This energy can then be used for their life processes.
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 occupied by an organism in a food chain is known as its trophic level. In the example above:
Food chains are rarely longer than four trophic levels as energy is used up or lost at each level.
|Organism||How it gets its energy|
|Producer||Using light energy to produce food by photosynthesis|
|Primary consumer||Eating producers, most are herbivores|
|Herbivore||Eating only plants|
|Secondary consumer||Eating primary consumers, most are carnivores|
|Carnivore||Eating only other animals|
|Tertiary consumer||Eating secondary consumers|
|Omnivore||Consumers which eat both animals and plants, so can occupy more than one trophic level in a food chain|
|Decomposer||Feeding on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces|
A vole gets its energy from eating grass, but also eats insects. This makes it both a primary and secondary consumer. Which term from the table above could be used to describe the vole?