ACARA v9 CONTENT DESCRIPTION “explain the roles and interactions of consumers, producers and decomposers within a habitat and how food chains represent feeding relationships”
Builds on knowing that living things have features that help them survive. Here we look at a whole habitat and the three jobs that keep it going: producers, consumers and decomposers, and how food chains show what eats what.
Three jobs in every habitat
A habitat is the place where living things make their home, such as a patch of bushland or a grassy paddock. The living things in it can be grouped by what they do for food. A producer, like a gum tree or grass, makes its own food. A consumer, like a grasshopper or a kookaburra, eats other living things. A decomposer, like a fungus or an earthworm, breaks down dead plants and animals. A healthy habitat needs all three.
Sort the organisms by their job
Tap a living thing in this bushland habitat to reveal whether it is a producer, a consumer or a decomposer.
A producer like the gum tree makes its own food. A consumer like the grasshopper or kookaburra eats other living things. A decomposer like a fungus or an earthworm breaks down dead things. Every habitat needs all three jobs.
Food chains show what eats what
A food chain is a simple way to show feeding relationships. We draw an arrow from the food to the animal that eats it, because the arrow follows the energy. Grass to grasshopper to small bird means the grasshopper eats the grass and the small bird eats the grasshopper. The chain almost always starts with a producer, because that is where the energy enters the habitat.
Build a food chain
Add each arrow in turn. An arrow points from the food towards the animal that eats it, showing which way the energy flows.
Grass is eaten by the grasshopper, and the grasshopper is eaten by the small bird. Each arrow points from the food to the eater, the same way the energy moves along the chain.
Producers capture the energy of the sun
Producers are special because they can make their own food using sunlight. That is why a plant grows in the light but cannot feed itself in the dark. Consumers cannot do this at all, so they have to eat producers or other consumers to get their energy. This is the reason a food chain has to begin with a producer.
Producers make food from sunlight
Turn the sun on and off. A producer only makes its own food when sunlight reaches it, something a consumer can never do.
A producer uses sunlight to make its own food, so the plant only gains energy when the sun is on. Consumers cannot do this, which is why every food chain starts with a producer.
Decomposers keep nutrients moving
Nothing in a habitat is wasted. When a leaf or an animal dies, decomposers break it down and return the nutrients to the soil. New plants take up those nutrients and grow, so the same matter is used again and again. Without decomposers, dead material would pile up and plants would run short of the nutrients they need.
Decomposers return nutrients
Step around the loop. A decomposer breaks down a dead leaf into nutrients in the soil, which then feed a brand new plant.
When a leaf dies, decomposers break it down into nutrients that go back into the soil. Those nutrients feed a new plant, so the matter goes round and round instead of being lost.
The living things interact
Because each living thing depends on others for food, a change to one part of a habitat can affect many others. If the grass is removed, the grasshopper has nothing to eat, and then the small bird that ate the grasshopper goes hungry too. Looking at food chains helps us see how the producers, consumers and decomposers in a habitat are all linked together.
Remove a link from the chain
Take one organism out of the habitat. See which other living thing loses the food it depends on.
The living things in a habitat depend on each other. Take away the grass and the grasshopper has nothing to eat. Take away the grasshopper and the small bird goes hungry. One change can affect many others.
Why this matters
Food chains and habitats are all around us, from a bush garden to a creek. Knowing the roles of producers, consumers and decomposers, and reading the arrows in a food chain, helps you understand how living things rely on each other. It also helps you see why caring for one part of a habitat helps protect the whole community of living things.
Quick self-check
1. A gum tree makes its own food from sunlight. What role does it have in a habitat?
2. In a food chain, which way does an arrow point?
3. What is the main job of a decomposer such as a fungus or an earthworm?
4. In the chain grass to grasshopper to small bird, what happens if all the grass is removed?
5. Why does every food chain begin with a producer?