1. Food Chains and Food Webs Food chains and food webs show the feeding relationships, and thus the energy flow, among organisms. A food chain shows one pathway of energy flow among organisms in an ecosystem.

2. Food Chains and Food Webs Because only about 10% of the energy is transferred from one trophic level to the next, there is not enough energy at the higher levels to support additional levels. For this reason, food chains are usually short, consisting of only a few organisms.

4. Food Chains and Food Webs  A food web is a group of interconnected food chains.  A food web is different from a food chain because it provides a more accurate and detailed picture of how organisms feed within an ecosystem.  An organism typically gains energy from several sources and is food for many others.

5. Food Chains and Food Webs  The arrows in food chains and food webs show the flow of energy in one direction in an ecosystem.  The basis of any food chain or food web are producers.  Decomposers may or may not be included in food chains and food webs.

8. 1° producer 2° 2°, 3° 2° 3° 2°, 4°

9. X ? ↑ ↑↑ ↑

10. X ? ↓ ↓ ↓ ↑

11. 20,000 kilocalories 2,000 kilocalories 200 kilocalories

12. 20,000 kilocalories 2,000 kilocalories 200 kilocalories 20 kilocalories