Food chains and trophic levels
Arrows show the direction of energy flow.
A food chain is the simplest representation of feeding relationships. ARROWS point from the EATEN to the EATER β they show the direction of energy and nutrient flow.
Example: Grass β Rabbit β Fox β (Eagle).
Each step is a trophic level:
| Trophic level | Name | Example |
|---|---|---|
| 1 | Producer | Grass, algae, oak tree |
| 2 | Primary consumer (herbivore) | Rabbit, cow, caterpillar |
| 3 | Secondary consumer | Fox, frog, small bird |
| 4 | Tertiary consumer | Eagle, lion |
Producers are usually plants. They make their own food by photosynthesis β the ENERGY ENTRY POINT for the whole ecosystem.
Consumers eat other organisms. Herbivores eat plants; carnivores eat animals; omnivores eat both.
Decomposers (bacteria and fungi) feed on dead bodies and waste. They aren't usually shown in food-chain arrows but they're vital: they recycle nutrients back to the producers.
- Arrows point from eaten β eater.
- Trophic levels: producer β primary cons. β secondary cons. β ...
- Decomposers recycle dead material back into the system.