Food Chains & Energy Transfer
Construct and interpret food chains identifying producers, predators, and prey, and understand energy transfer between trophic levels
What a learner can do afterwards
- Construct a food chain with at least four organisms, labelling producer, primary consumer, predator
- Define producer, predator, and prey with examples
- Interpret a given food chain to predict what happens if one organism is removed
1 · Read
You have used producer and consumer before. A food chain shows one feeding path. Plants and algae in our examples use sunlight to make food. They are producers. Consumers get food by eating. List organisms from food to eater. Count each listed organism once. Sunlight supplies energy but is not an organism.
The primary consumer eats the producer: here, the water flea eats algae. Count consumers by counting organisms that eat, leaving out the producer. A predator hunts another animal for food; prey is the animal it hunts. The small fish is predator of water fleas and prey for perch. The heron is the last predator shown, not proof that nothing hunts it elsewhere.
Only some food energy becomes stored in an eater's body. Living things use energy and release heat. Some food is not eaten or digested. Less energy supports each later feeding level, or group of eaters. This helps limit chain length, without setting one fixed maximum. It compares whole feeding levels, not the energy inside individual animals.
If water fleas disappear, small fish lose one food source. Small-fish numbers could fall, leaving less food for perch. Losing a producer can also reduce food along its chain. Other foods may change the result, so these are possible changes rather than certain outcomes.
If perch leave, fewer small fish may be hunted. Small-fish numbers could rise. More small fish could then eat more water fleas, reducing water-flea numbers. Other predators, food supplies and disease also matter. To predict a change, check both what an animal eats and what eats it.
Food chains trace energy from food to eater. Less energy supports later feeding levels. Removing a link can affect its food and predators, but outcomes vary.
Lesson, questions and flashcards written for this dataset. Ecology references were consulted to check the science.
Readings and flashcards written for this dataset.
More to read
Build a pond feeding path
Suppose algae make food using sunlight. A shrimp eats the algae, a fish eats the shrimp, and a heron eats the fish. Start with the food and follow each eater: algae → shrimp → fish → heron.
The shrimp is the primary consumer because it eats the producer. Fish and herons are consumers too. The fish is a predator of the shrimp and prey for the heron. This path leaves out other foods these animals might eat.
Food energy does not all pass on
A predator does not receive all the energy that entered the feeding level below it. Some animals are never eaten. Animals also release heat while using energy, and some food leaves their bodies undigested.
These transfers leave less energy to support later feeding levels. That helps explain why food chains are usually short. It does not give every chain the same maximum length, or tell us how much energy is inside one particular animal.
Check a prediction
Imagine grass feeds grasshoppers, grasshoppers feed frogs, and frogs feed herons. Fewer frogs would leave herons with fewer frogs to eat. Grasshoppers might also be hunted less.
Would herons certainly disappear? The chain cannot tell us. They may have other foods. Grasshopper numbers also depend on plants, disease and other predators. Use the links to explain what could change, then say what else you would need to know.
2 · Watch
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Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
24 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.