Food webs
The idea
A food web represents feeding relationships. In a common convention, arrows point from food to the organism consuming it, showing energy transfer. Producers capture energy, consumers eat organisms, and decomposers break down organic matter. Real ecosystems are more complex than a short chain.
Worked example
Grass → rabbit → fox shows energy moving from grass to rabbit to fox. A rabbit may eat other plants, and a fox may eat other animals, creating a web.
Another application
Leaves → caterpillar → bird shows two transfers. If caterpillars decline, some birds may switch food sources while others may be affected more strongly; a web helps represent those alternatives.
A common misunderstanding
Arrow conventions should be stated explicitly. In a food web showing energy transfer, the arrow points toward the consumer, not toward its food.
Try it yourself
Draw a web with six organisms. Add a key explaining arrow direction. Predict how a change in one population could affect another, noting uncertainty.
Check your understanding
In grass → rabbit, which receives energy from the other?
Reveal the explained answer
The rabbit receives energy by consuming grass.