Food Webs
- A food web is a network of interconnected food chains
- Food webs are more realistic ways of showing connections between organisms within an ecosystem (compared to individual food chains) as animals rarely exist on just one type of food source
Food Web Definitions Table
A food web shows the interdependence of organisms
- Food webs give us a lot of information about the transfer of energy in an ecosystem
- They also show interdependence - how the change in one population can affect others within the food web
- For example, in the food web above, if the population of earthworms decreased:
- The population of grass plants would increase as there are now fewer species feeding off them
- The populations of frogs and mice would decrease significantly as earthworms are their only food source
- The population of sparrows would decrease slightly as they eat earthworms but also have another food source to rely on (caterpillars)
Examiner Tip
Don’t forget – animals (known as consumers) can be at different trophic levels within the same food web as they could be omnivores (animals that can eat both plants and animals) or could be predators that eat both primary, secondary and/or tertiary consumers!
Trophic levels for a simple food web – note that some organisms can belong to more than one trophic level (such as the squirrel, fox and eagle in this food web)
