1. Food Webs and Energy Flow
November 9/10

2. Do Now Why do we eat? Grab one of our brandy-spankin’ new Trackers
Start working on today’s warm-up:
Why do we eat?

3. New Class Procedures Warm-up/Exit ticket trackers Class log
If you arrive late
If you leave class for any reason
New class website: DrMooreScience.com

4. Grades are updated Work is returned to you in your hanging file
You can (and SHOULD) make up any work that scores less than 75% of its point value

5. Objective
By the end of class, students will be able to:
Explain why plants are more abundant in ecosystems than top predators.

6. Why do we eat?

7. Why do we eat?
To gain matter
To gain energy

8. Matter versus Energy Matter is physical stuff
Energy is the ability to change matter

9. Matter cycles, energy flows
The Earth does not gain or lose great amounts of matter
Matter on Earth is recycled

10. Matter cycles, energy flows
The Earth gains energy in the form of solar radiation and loses energy as heat
Energy flows through Earth

11. Matter versus Energy Matter ≠ Energy
But energy can be stored in matter

12. Why do we eat?
To gain matter
To gain energy

13. Why do we eat?
A “Calorie” is a unit of energy

14. Why do we eat?
In Europe, they use the word “Energy” on their nutrition labels instead of “Calories”

15. Food webs show the flow of energy through an ecosystem

16. Arrows show movement of energy (always point to the predator)

17. Yellowstone National Park Food Web
In each relationship, the arrow points to the predator.
Pond algae is eaten by mayflies and cutthroat trout.
Bearded wheatgrass and sagebrush are eaten by elk, bison, snowshoe hares, and deer mice.
Gray willow leaves are eaten by deer mice, elk, and bison.
Aspen trees are eaten by beavers. The leaves are eaten by elk.
Mayflies are eaten by harlequin ducks, grizzly bears, and deer mice.
The snowshoe hare is eaten by coyotes, wolves, and foxes.
Cutthroat trout are eaten by bald eagles and grizzly bears.
Beavers are eaten by coyotes and gray wolves.
Harlequin ducks are eaten by red foxes and bald eagles.
Deer mice are eaten by coyotes, red foxes, grizzly bears, and bald eagles.
Elk and bison are eaten by coyotes and gray wolves.
Gray wolves may also feed on coyotes and red fox.

18. What do the arrows show the flow of?
Why are arrows always drawn from prey to predator?

19. Some organisms don’t eat anything!

20. Organisms that make their own food are called..
Autotrophs or
Primary producers

21. Organisms that make their own food are called..
Autotrophs or
Primary producers
Plants produce their own food through PHOTOSYNTHESIS

22. Organisms that make eat other things for food are called..
Heterotrophs or
Consumers

23. Classifying Consumers
Herbivores eat only plants

24. Classifying Consumers
Carnivores eat only animals

25. Classifying Consumers
Omnivores eat plants and animals

26. Classifying Consumers
Decomposers eat remains and wastes of other organisms

27. Trophic Levels
Steps in a food chain

28. Trophic Levels Primary producers get energy from sunlight
MOST of the energy they use
SOME of the energy moves into the atmosphere as heat
10% of the energy is stored in plant tissues
Only this energy is available to the next trophic level!

29. Trophic Levels Primary consumers get energy from primary producers
MOST of the energy they use
SOME of the energy moves into the atmosphere as heat
10% of the energy is stored in body tissues
Only this energy is available to the next trophic level!

30. Trophic Levels Secondary consumers get energy from primary consumers
MOST of the energy they use
SOME of the energy moves into the atmosphere as heat
10% of the energy is stored in body tissues
Only this energy is available to the next trophic level!

31. Trophic Levels
Tertiary consumers get energy from secondary consumers

32. 10% Rule
Only 10 percent of the energy in one trophic level is transferred to the next trophic level
If we start with 1000 calories of grass, how many calories will make it into the rabbit?
How many calories will be transferred to the fox?
How many calories will be transferred to the wolf?

33. Energy Pyramid
It takes a large number of producers to support a small population of primary consumers
It takes a large number of primary consumers to support a small population of secondary consumers
Etc.

34. This is why primary producers are the most abundant organisms in ecosystems
Let's check this out at Yellowstone right now!

35. Biomagnification
Concentrations of toxins increase as you move up the food chain

36. Biomagnification

37. Trophic Cascades The effects of top predators on ecosystems
How Wolves Change Rivers

38. Kahoot!
Let's test ourselves!

39. Exit ticket
Using complete sentences, explain why only 10% of the energy in one trophic level gets transferred to the next trophic level in an energy pyramid.
(Hint: Where does the rest of the energy go?)