1. Energy Models

2. Energy
Energy must flow through an ecosystem for the system to remain stable.
Organisms must eat other organisms.

3. Food Chains Food chains show the eating patterns in an ecosystem.
Food energy flows from one organism to another.

4. Food Chains leaves → grasshopper → frog → snake → hawk Cannot be:
leaves → caterpillar → spider → frog → lizard → fox → hawk
Why?

9. Food Chains Are the interactions between organisms really this simple?
In an ecosystem there are many food chains, even for the same organism.

10. Food Webs
Food webs show the feeding relationships between many organisms in an ecosystem.
More arrows, but still shows the flow of energy.

14. Energy Flow
Only about 10% of one organism’s energy is transferred to the organism that eats it.