Food Webs (HL IB Environmental Systems & Societies (ESS))

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 as consumers rarely feed on just one type of food source

• Compared to food chains, food webs give us a lot more information about the transfer of energy in an ecosystem

• They also show interdependence (how a 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)