1. Energy Flow and Pyramids of Numbers Science - Chapter 2

2. Review – Food Webs Identify 5 food chains from the food web.

3. Think About It … Do food chains and food webs show us how many prey are consumed by their predator? Do food chains and food webs tell us how many producers are required in order for a consumer to survive?

4. Energy Flow and Pyramids of Numbers Food chains and food webs help organize the information about relationships between organisms in an ecosystem. Food chains and food webs show how energy is transferred through an ecosystem.

5. Energy Flow and Pyramids of Numbers Food chains and Food webs do not show how many organisms are involved in the energy transfer. For example: Exactly how many hares will a lynx eat?

6. Energy Flow and Pyramids of Numbers Food chains and Food webs do not show how many organisms are involved in the energy transfer. For example: Exactly how many hares will a lynx eat?

7. To solve this problem, ecologists build a pyramid of numbers. Energy Flow and Pyramids of Numbers

8. Pyramid of Numbers A pyramid of numbers is a model of an ecosystem that represents the number of organisms consumed at each level.

9. A pyramid of numbers includes the same organisms that you would find in a food chain. Each level in the pyramid represents the number of organisms involved at that level. Pyramid of Numbers

10. There are always more animals being eaten than there are animals eating. The producers always form the broad base, with all of the consumers in different levels above. Pyramid of Numbers

11. For Example: One hawk Three woodpeckers Six grasshoppers