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
The lesson
You already know a food chain shows who eats whom, starting with a producer and ending with a predator. Now let's add something new: energy. Every bit of energy in a food chain starts with the sun, and each living thing that eats only gets to keep some of it.
Start with the oak tree. It is the producer, since it makes its own food from sunlight. The caterpillar eats oak leaves, so it's the primary consumer. The robin eats the caterpillar, and the hawk eats the robin. The hawk is the top predator: nothing in this woodland hunts and eats it.
Energy shrinks at every step. The oak tree captures sunlight to grow leaves. When the caterpillar eats those leaves, it only keeps some of that energy, since the tree already used part of it to live and grow. The same happens when the robin eats the caterpillar, and again when the hawk eats the robin. That's why food chains rarely stretch past four or five living things: there isn't enough energy left to support more.
If you remove one organism from a food chain, everything connected to it changes too. Losing the caterpillars would leave robins with less food, and losing the robins would leave hawks with less food.
Energy flows from producer to predator, shrinking at every step, and removing one link changes the whole chain.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 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.