Food webs

A food web is a network of interconnected food chains. It shows the energy flow through part of an ecosystem.

Here is an example of a food web diagram:

Food web. Oak tree provides food for squirrels, caterpillars, fungi and earthworms. Earthworms are eaten by shrews and wood mice, which are eaten by owls. Wood mouse and squirrel are eaten by foxes.A woodland food web

In a food web, changes in the population of one organism have an effect on the populations of other organisms. This is called interdependence.

Question

How many different food chains can you see in this food web?

Six

  • Oak tree – squirrel - fox
  • Oak tree - caterpillar - shrew - owl
  • Leaf litter - fungi
  • Leaf litter – earthworm – shrew - owl
  • Leaf litter - earthworm - wood mouse - fox
  • Leaf litter – earthworm - wood mouse - owl
Question

What would happen to the numbers of caterpillars if the population of wood mice decreased?

They would increase. The owls would prey on the shrews more as there were fewer wood mice. This means there would be fewer shrews to feed on the caterpillars and their numbers would increase due to lack of predation.

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