Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!

Science

Food chains

Print

Changes to food webs

Let's look at the food web again and ask some questions about its predator-prey relationships, with some possible answers.

Food web - The producer is grass, which is eaten by rabbits, insects and slugs. The rabbit is eaten by the fox. The insects are eaten by frogs, voles and thrushes. Thrushes also eat the slugs. Frogs, voles and thrushes are eaten by a hawk. Frogs and voles are also eaten by the fox.

What would happen if the grass died?

The grass is the producer, so if it died the consumers that feed on it - rabbits, insects and slugs - would have no food. They would starve and die unless they could move to another habitat. All the other animals in the food web would die too, because their food supplies would have died out. The populations of the consumers would fall as the population of the producer fell.

What would happen if the population of slugs decreased?

Slugs, rabbits and insects all eat grass. If there were fewer slugs there would be more grass for the rabbits and insects. With more food the populations of rabbits and insects would increase. However, the thrushes would have to eat more insects to maintain their population, so it is also possible that the population of insects could decrease. This is turn may reduce the populations of voles and frogs.

What would happen if the population of insects decreased?

There would be more food for the rabbits and slugs, so their populations would increase. However, there would be less food for the frogs and voles, so their populations would decrease. This means less food for the foxes and hawks. However, there are likely to be more rabbits and thrushes for them to eat, so their populations are likely to stay the same.

Activity

Food chains activity

Hungry for knowledge? Prey on this activity.

Play

Whack Attack

Whack and zap mad professors and aliens!

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.