1. Energy Flow in Ecosystems
Chapter 3-3
Energy Flow in Ecosystems

2. Daily Objectives Trace the flow of energy through living systems.
Identify the three types of ecological pyramids

3. Trophic Levels Each link in a food chain is known as a trophic level.
Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem.

4. Trophic Levels
Biomass - The amount of organic matter comprising a group of organisms in a habitat.
As you move up a food chain, both available energy and biomass decrease.
Energy is transferred upwards but is diminished (reduced) with each transfer.

5. Trophic Levels Primary Consumers (Herbivores) Producers (Autotrophs) E
Secondary Consumers
(Small Carnivores)
Primary Consumers (Herbivores)
Producers (Autotrophs) E N R G Y
Tertiary Consumers – Top Carnivores
0.1% 1%
10%
100%

6. Ecological Pyramids
Show the relative amount of energy or matter contained within each trophic level in a given food chain or food web.

7. Energy Pyramid
Show the relative amount of energy available at each trophic level of a food chain or food web.
On average, about 10 percent of the energy available within one trophic level is transferred up to the next trophic level.

8. Biomass Pyramid
A pyramid of biomass illustrates the relative amount (mass) of living organic matter available at each trophic level in an ecosystem.

9. Numbers Pyramid
A pyramid of numbers shows the relative number of individual organisms at each trophic level in an ecosystem.

10. Food Chain
A simple model that shows how matter and energy move through an ecosystem.

11. Food Web
Shows all possible feeding relationships in a community at each trophic level.
Represents a network of interconnected food chains.
Food webs are complex, so it is often difficult to predict exactly how they will respond to environmental changes.

12. Food Web

13. Food Chain Food Web
- Just 1 Path of Energy All Possible Energy Paths