1. SC.912.L.17.9
Use a food web to identify and distinguish producers, consumers, and decomposers.
Explain the pathway of energy transfer through trophic levels and the reduction of available energy at successive trophic levels.
Essential Question: How does the amount of energy change as it moves through an energy pyramid?

2. Bell Ringer
A diagram of a food web is shown below. Which organism receives the least amount of energy from the producers? A. Grasshopper B. Hawk C. Mouse D. Rabbit
Have students work on questions for 1-2 minutes each.

3. Bell Ringer A team of ecologists observed feeding
patterns of several populations in the
desert. The energy pyramid shown on the
right depicts the feeding patterns the
ecologists observed. Which of the following
best explains the difference in the amount of
available energy in the trophic levels of the
desert ecosystem?
A. There is less energy available in the
producers because their tissues are less
dense than those at higher trophic levels.
B. There is more energy available in the second trophic level because less energy is needed for hunting compared to the higher trophic levels.
C. There is less available energy in the fourth trophic level because of the loss of energy through metabolism in each of the lower trophic levels.
D. There is more available energy in the birds of prey because they have greater muscle mass for storing energy than organisms in lower trophic levels have.

4. Background Facts
In earlier grades, you learned about producers and consumers like herbivores (plant eaters), carnivores (meat eaters), and omnivores (eats plants and meat).
You learned about decomposers like microorganisms, termites, worms, and fungi.
You also learned about the roles of predators and prey, and about parasites and their hosts.
Discuss all highlighted terms with students and their relationships

5. Producers & Consumers
The trophic levels of a food chain are numbered according to how far the particular organism is along the chain.
Producers are at level 1. (Plants are producers because they produce their own food.)
Herbivores are at level 2. (Consumers are organisms that need to eat other organisms to survive.)
Predators or higher order consumers are at level 3 or above.
And so on…

7. Food Chains
Food chains use pictures or words and arrows to show the movement of energy through the trophic levels of organisms living in a community.
The trophic level of an organism indicates the position that the organism occupies in the food chain.
It shows what it eats and what eats it.

8. Trophic Levels Primary consumer: consumer that eats the producer
Secondary consumer: eats the primary consumer
Tertiary consumer: eats the secondary consumer
Note the trophic level of each organism
Trophic Structure video:

10. Food Webs
Food webs describe the organisms found in interconnecting food chains using pictures or words and arrows.
In other words, food webs are a bunch of food chains all together!
They describe the complex patterns of energy flow in an ecosystem by modeling who consumes whom or what.

11. How many food chains can you identify in this food web?
Discuss with students and have them identify how many food chains are present.
How many food chains can you identify in this food web?

12. Energy Pyramids
An energy pyramid shows the amount of energy that moves from one trophic level to another in a food chain.
The most energy is available at the producer level of the pyramid.
The availability of energy decreases as it moves up the energy pyramid.

13. The most energy is at the producer level – the base of the pyramid.

14. 10% Rule
An energy pyramid shows the amount of energy (10%) that moves from one trophic level to another in a food chain.
The remaining 90% will have been used by the consumed organism for its metabolism.

15. Discuss with your partner:
Which organism has 1% of the energy found in the producer?
Answer: the snake

16. Discuss the energy transfer

17. We Do: Making a Model Let’s make a model of an energy pyramid.
The model you will construct will be simple. It will show pictures of the producers and consumers at each level, and the names in words.
You will have to add trophic levels and the labels for each organism.

19. Bell Ringer
A diagram of a food web is shown below. Which organism receives the least amount of energy from the producers? A. Grasshopper B. Hawk C. Mouse D. Rabbit

20. Bell Ringer A team of ecologists observed feeding
patterns of several populations in the
desert. The energy pyramid shown on the
right depicts the feeding patterns the
ecologists observed. Which of the following
best explains the difference in the amount of
available energy in the trophic levels of the
desert ecosystem?
A. There is less energy available in the
producers because their tissues are less
dense than those at higher trophic levels.
B. There is more energy available in the second trophic level because less energy is needed for hunting compared to the higher trophic levels.
C. There is less available energy in the fourth trophic level because of the loss of energy through metabolism in each of the lower trophic levels.
D. There is more available energy in the birds of prey because they have greater muscle mass for storing energy than organisms in lower trophic levels have.

21. Exit Ticket Question #1
The Atlantic Ocean, which border’s Florida coastline, has many interconnecting food webs that link its marine life. Which of these organisms would MOST LIKELY be found at the top of an energy pyramid?
Clams
Kelp
Sardines
Sharks
Answer D

22. Exit Ticket Question #2
In this marine trophic pyramid, there are several levels of consumers. What type of consumer is the herring, and what is its proper label? A. primary consumer, herbivore B. primary consumer, carnivore C. secondary consumer, herbivore D. secondary consumer, carnivore
D. secondary consumer, carnivore

23. Exit Ticket Question #3
In this marine trophic pyramid, the phytoplankton on the first level contain 1250 kcal of energy. How many kcal would be available for the fish that eats the herring? A kcal B. 125 kcal C kcal D kcal
D kcal

24. Essential Question
Using the SRE method (statement, reason, & evidence), answer the Essential Question on the left side of your Interactive Journal. How does the amount of energy change as it moves through an energy pyramid?