1. Energy Flow in Ecosystems
Everything that organisms do requires energy.
Every species must
somehow get food for
energy.

2. The Sun
Sunlight is the primary energy source for most forms of life on Earth.

3. Producers
Photosynthetic organisms change light energy into energy they can use to grow.
Examples: plants, algae

4. Producers are autotrophs, meaning they make their own food.
They are the basic food source for an ecosystem.

5. Consumers
Organisms that eat other organisms instead of producing their own food.

6. Consumers are heterotrophs, meaning they rely on other organisms for energy.

7. Types of Heterotrophs
Herbivores – Obtain energy by eating only plants.

8. Carnivores – obtain energy by eating only animals.

9. Omnivores –Obtain energy by eating both plants and animals.

10. Decomposers
Organisms that break down the remains of animals and plants.
Examples: bacteria and fungi

11. Energy Flow
In an ecosystem, energy flows from the sun to producers to consumers to other consumers and on to decomposers.

12. Food Chain
a series of steps in which organisms transfer energy by eating and being eaten

13. Food Web
links all of the food chains in the ecosystem together

14. Energy in an Ecosystem
Energy is stored at each step in a food chain or food web, but the amount becomes less at each level.

15. Trophic Levels
Each step in the transfer of energy through an ecosystem is called a trophic level.

16. Loss of Energy
When a zebra eats 20 pounds of grass, the zebra does not gain 20 pounds. Why not?
Where did the energy go?

17. The 10 percent rule
When a zebra or a caterpillar eats grass, some of the energy is stored in the zebra or caterpillar.
Most of the energy, however, does not stay with the zebra.
As the zebra uses energy from the grass to run and grow, the energy is changed to heat energy.

18. Energy is lost as heat
The zebra does not keep 90% of the energy it gets from the grass.
Only about 10% of the energy from the grass becomes part of the zebra’s body.
This amount of stored energy is all that is available to organisms at the next trophic level that eat the zebra.

19. Energy Pyramid A diagram that shows an ecosystems’ loss of energy.
Each layer in the energy pyramid represents one trophic level.
The lowest level, the producers, have the most energy.

20. Energy Pyramid
Herbivores have less energy and make up the second level.
Carnivores that feed on herbivores make up the higher level.
The energy stored at each level is about 1/10th the energy stored in the level below.

21. Top Carnivores are Rare!
Big predators are rare compared to herbivores.
A lot more energy is required to support a single predator than a single herbivore.
Many ecosystems do not have enough energy to support a large population of predators.

22. Carrying Capacity
The largest population that an ecosystem can support at any given time.