A food chain follows energy along one path: grass → rabbit → fox. Real ecosystems are messier. A rabbit is eaten by foxes and hawks, and a fox eats mice and rabbits. Link all the chains together and you get a food web. The roles come from Producers, Consumers and Decomposers.
Key idea
In food chains and webs, the arrow points from the food to the eater. It shows the direction energy and matter move: grass → rabbit means the rabbit eats the grass.
Why it works
Read every arrow as "is eaten by" or "gives energy to." Energy enters from the sun into the producers, so every arrow path starts at a producer and points up toward the top predators. If the arrows pointed the other way, energy would flow from the fox into the grass, which never happens.
Worked example: Count the chains
In the meadow web, how many food chains end at the fox?
- The fox eats mice and rabbits.
- Chains to the fox through the rabbit: grass → rabbit → fox. That is 1.
- Chains through the mouse: grass → mouse → fox, and grass → grasshopper → mouse → fox, and flower → grasshopper → mouse → fox. That is 3.
- Total: 1 + 3.
Answer: 4 food chains end at the fox.
Worked example: Trophic levels
In the chain grass → grasshopper → robin → hawk, which level is the robin?
- Producers are level 1: grass.
- Primary consumers (herbivores) are level 2: the grasshopper.
- Secondary consumers are level 3: the robin.
Answer: The robin is a secondary consumer (level 3).
Common mistake
Students draw the arrows from the eater to the food, as if the arrow meant "eats." Then "fox → rabbit" looks right but is backward. Check: does your arrow path start at a plant or alga? Energy always starts with producers.