Food Webs

This lesson covers: 

  1. The difference between food chains and food webs
  2. Key terminology related to feeding interactions
  3. How organisms are interdependent in food webs

Food chains versus food webs

Diagram showing a food web with carrots, grasses, wheat, rabbits, mice, grasshoppers, foxes, owls, and birds illustrating the transfer of energy.

Food chains show feeding relationships between different organisms whereas food webs show how food chains interconnect in an ecosystem.

Feeding interactions - Producers and consumers

Diagram showing a food web with producers like carrots, grasses, and wheat, and consumers like rabbits, foxes, mice, owls, birds, and grasshoppers.

These terms are used to describe organism roles within food webs:

  • Producer - Plants that generate food and energy for the ecosystem (shown in green above, e.g. carrots, grasses and wheat).
  • Consumer - Heterotrophs that rely on other organisms for food (shown in red above).

Feeding interactions - Types of consumer

Diagram showing a food web with producers like carrots, grasses, and wheat, and consumers such as rabbits, mice, grasshoppers, birds, owls, and foxes.

Consumers can be divided into:

  • Primary consumers - Animals that eat producers (shown in red above, e.g. rabbits).
  • Secondary consumers - Animals that eat primary consumers (shown in purple above, e.g. owls).
  • Tertiary consumers - Animals that eat secondary consumers (shown in orange above, e.g. foxes when they eat birds).


Some animals can occupy more than one role. For example birds are primary consumers when the eat wheat but secondary consumers when they eat grasshoppers.

Feeding interactions - Carnivores, herbivores and omnivores

Diagram showing the transfer of energy in a food web with producers like carrots, grasses, and wheat, and consumers like rabbits, mice, grasshoppers, birds, owls, and foxes.

These terms are used to describe what consumers eat:

  • Herbivore - Animals that only consume producers/plants (shown in teal, e.g. grasshoppers).
  • Carnivore - Animals that only eat other consumers (shown in red, e.g. owls).
  • Top carnivore - Carnivores not predated within that food web (shown in orange, e.g. foxes).
  • Omnivore - Animals that eat both plant and animal matter (shown in blue, e.g. birds).

Interdependency in food webs

The arrows in food web diagrams demonstrate the flow of energy between organisms.


This interdependency means a change in one organism's population can affect other organisms that depend on it for food.

Diagram showing the interdependency in a food web with arrows indicating the flow of energy between organisms such as rabbits, foxes, owls, grasshoppers, birds, and the impact of the loss of wheat on mice.

For example:

  • If a disease kills all the wheat plants, mice will not longer have a food source and will die.
  • This means they foxes also have less food to eat so their population would also decline.