Science
What is a food chain?
Quick answer
A food chain shows who eats whom in nature, starting with a plant that makes its own food and following the energy as it passes from one living thing to the next.
In one sentence
A food chain shows how energy passes from one living thing to the next when it is eaten, starting with a plant and following who eats whom, like grass → rabbit → fox.
Explained
Every animal needs food for energy. Almost all of it starts with the Sun. Plants capture sunlight and use it to make their own food through photosynthesis. That is why plants are called producers.
Animals cannot make their own food, so they are consumers. A rabbit eats grass and gets some of the energy the grass stored. A fox eats the rabbit, so the energy moves on again:
grass → rabbit → fox
The arrows point the way the energy goes. Read each arrow as "is eaten by".
The links in a food chain
| Link | What it does | Example |
|---|---|---|
| Producer | makes its own food from sunlight | grass |
| Primary consumer | eats the producer (a herbivore) | rabbit |
| Secondary consumer | eats the primary consumer | fox |
| Apex predator | at the top; nothing usually hunts it | lion, orca |
| Decomposer | breaks down dead things | worm, fungi |
An animal that hunts is a predator, and the animal it hunts is its prey.
Why are food chains short?
Each animal uses most of its energy just to move, grow and keep warm, so only a small part (roughly a tenth) passes to the next link. That is why there are many more plants than rabbits, and more rabbits than foxes, and why chains rarely have more than four or five links.
Food chains and food webs
Real animals eat many foods, so in an ecosystem lots of food chains join into a food web. If one link disappears, others feel it: fewer rabbits means hungrier foxes, and more grass left uneaten.
Examples
- Garden: lettuce → slug → thrush → cat
- Ocean: tiny algae → krill → whale
- Savanna: grass → zebra → lion
- Pond: pondweed → tadpole → fish → heron
Common mistakes
- Drawing the arrows backward. The arrow points to the eater: grass → rabbit, not rabbit → grass.
- Starting with an animal. Food chains begin with a producer, usually a green plant or algae.
- Thinking animals only eat one thing. A fox also eats mice, birds and berries.
- Forgetting decomposers. Worms, fungi and bacteria break down dead things and return nutrients to the soil.
Quick quiz
Food chains
Check what you know with 4 quick questions.
Question 1 of 4
What is at the start of almost every food chain?
Practise it
Try it
Pick a habitat such as a pond or park and write a food chain with at least three links. Then check yourself:
- In seeds → mouse → owl, which is the producer?
- Which animal is the prey?
- What does the arrow mean?
- If all the owls disappeared, what might happen to the mice?
Answers: 1) Seeds. 2) The mouse. 3) "Is eaten by." 4) There would probably be more mice, and they would eat more seeds.
Practise it step by step in a full course: Grade 4 Science
For grown-ups
Related topics
Photosynthesis
Photosynthesis is how green plants make their own food. They use energy from sunlight to turn carbon dioxide from the air and water from the soil into sugar, giving out oxygen.
Habitats
A habitat is the natural home of a living thing, where it finds the food, water, shelter and space it needs to survive.
Living things
Living things are organisms that grow, feed, get rid of waste, sense the world and reproduce. Plants, animals, fungi and bacteria are all alive.
Ecosystems
An ecosystem is a community of living things and the non-living environment they share, such as a pond, a forest or a coral reef. All the parts depend on each other.
Adaptation
An adaptation is a feature or behaviour that helps a living thing survive where it lives. A polar bear's thick fur and a cactus's spines are adaptations.
Amphibians
Amphibians are cold-blooded animals with thin, moist skin that live part of their lives in water and part on land. Frogs, toads, newts and salamanders are amphibians.