Food Webs

What eats what? Watch the 8 minute lion, wildebeest, alligator movie.

Listen to the "Feeding Frenzy" song. With your table mates, create your own food chain and plug into the Feeding Frenzy song board (p.19 here or p.2 here) for everyone to sing.

Part 1: Background Information

Discuss and write in journals the definitions of producer, consumer and decomposer.
- Producer=gets energy from sun,
- Consumer=gets energy from biotic things,
- Decomposer=releases the final drop of energy from biotic things.
In your journal, create a food chain (in the proper order) with the following:
- salmon
- phytoplankton (algae)
- herring
- zooplankton
- sun.
Properly label "producer," "1st order consumer," "2nd order consumer," and "3rd order consumer."

Alternative Option for Longer Class Periods:

Read the Food Chains Info and Vocabulary page and fill in the Food Chains sheet vocabulary section.

Read p. 25-29 about Mono Lake. Complete the second half of the Food Chains sheet (Mono Lake section).

Then watch the Mono Lake movie (start at minute 1:33 and watch for 7 minutes).

Read pp. 17-21 for definitions of producer, consumer, and decomposer.

Part 2: Producer/Consumer/Decomposer

Create lists of producers, consumers, and decomposers living in a local ecosystem (Elwha River, or forest for example).

Alternative Option for Longer Periods:

Sort the Mono Lake food web cards into producers, consumers, and decomposers.

Read pp. 19-21 as a full class.

If not done already, complete the Food Chains sheet.

Part 3: Trophic Levels

A trophic level is a group of organisms that share the same function in the food chain. Use the ecosystem and lists of producers, consumers, and decomposers you brainstormed in part 2 to complete the following task.

On a whiteboard, draw a large triangle with four rows and label the rows (from bottom) producers, primary consumers, secondary consumers, and tertiary consumers.
Add the sun below and decomposers off to the side.
Put your producers on first, then primary consumers, then the rest.
- Once the organisms are on the board, draw energy arrows connecting them.

See Mono Lake samples here. If you finish early, do the Food Chain Crossword.

Part 4: Energy Loss and Matter Cycling Notes

In your journal, copy these notes on energy loss and matter cycling.

Energy Loss:

Energy in ecosystems starts with the sun and ends up as heat going back to space.

Sun -> grass -> deer (90% loss, 10% biomass) -> cougar (90% loss, 10%biomass)

In food chains, only about 10% of the energy present in one step goes into the bonds of matter (biomass) in the next step.

The rest of the energy goes to:

Waste (to decomposers)
Movement (which goes to heat)
Maintenance (thinking, immune system, etc)

Matter Cycling:

Matter = atoms and molecules

Biomass = the organic matter (aka biotic factors) in an ecosystem.

The biomass in an ecosystem keeps getting re-arranged and it cycles through the ecosystem - it is not created nor destroyed, it just keeps cycling.

For example,

The matter in a leaf used to be air, water and soil,
The matter in a deer used to be that leaf, and
The matter in a cougar used to be that deer.
Eventually, the cougar dies and decomposers turn that cougar's matter back into soil, water and air to become a new leaf.

-----------------End of Notes to Copy---------------

Observe this Pac-Man Analogy for energy loss:

1g (3rd order consumer) .

10g (2nd order consumer) ..........

100g (1st order consumer)

....................................................................................................

1000g (producer)

....................................................................................................

Following the Pac-Man analogy, students read the Food Chains Info and Vocabulary page.

Also observe the Flow and Loss of Energy Diagram.

Use the two different scaffolded notes templates here as needed for individual students.

Part 5: Food Chain Energy Loss Relay

Energy is lost as it moves up a food chain. Using different-sized containers/seives and water, set up and then run a relay to model this energy loss.

Set-Up:

1. Mental Challenge: Using only a 3-gallon bucket and a 5-gallon bucket, figure out how to get exactly 4 gallons of water into the 5-gallon bucket
2. Using the 2 bucket method or not, put 4 gallons of water into the 5-gal. bucket.
3. Groups of 4 choose 4 organisms to role play an actual food chain.
4. On the goal line, set the bucket with the red "Producer" container and the student who will be the "Producer."
5. On the 25 yard line, put the white "1st Order Consumer" container and the student who will be the "1st Order Consumer."
6. On the 50 yard line, put the clear "2nd Order Consumer" container and the student who will be the "2nd Order Consumer."
7. On the 75 (opposing 25) yard line, put the "3rd Order Consumer" container and the student who will be the "3rd Order Consumer."

In the classroom, groups of 4 choose 4 actual organisms to role play and tell the teacher the organisms plus the proper trophic levels before they receive materials.

Relay:

1. When the teacher says go, "Producers" fill their red containers with water.
2. The "Producers" walk (not run) to the "1st Order Consumers," and dump the remaining water into the "1st Order Consumers" container.
3. "Producers" then walk back to their starting point and refill their container.
4. Repeat steps 2-3 with the "1st Order Consumers" and then the "2nd Order Consumers."
5. Run the relay until all of the water is gone from the starting bucket.
6. All students record in their journals how much water accumulated in their "3rd Order Consumer" cup.

Engineering Challenge:

If we start with 15,000 mL (approximately 4 gallons) of water/energy at the producer level, how many mL should be left (turned into biomass) at the 1st order consumer level? ___
1. Then, how many mL should be left at the 2nd order consumer level? ___
2. How many mL should be left at the 3rd order consumer level? ___
3. After running the relay, and based on the speeds of your team members and distances traveled, figure out how to get actual 90% energy loss at each trophic level. Write your plan for which yard lines to use.
4. Run your engineered relay, and if it does not achieve desired results, write a new plan and run it again.

Part 6: Elwha Estuary (Wetland) Food Web

Watch the Elwha River Nearshore from National Geographic (3:20).

With your group, make an Elwha Estuary (wetland) Food Web on 11"x17" paper.

See a complete and correct sample here.

1. Cut out and put your items on your food web and include all energy arrows.
2. Once your web is complete and checked by the teacher, glue your items in place (be sure you don't sneeze or bump the table in the meantime).
3. Include the title "Elwha Estuary Food Web," your period, table # and names.
4. Optional extension: color and decorate your organisms and your background.

For students who were absent on the day this was assigned, use the completed sample here to help answer the questions on the Elwha Wetland Food Web sheet.

A side note on the skill of timeliness:

Job announcements like these for local jobs (that former PA students frequently get) come up all the time and are dependent on timeliness. In April, 2018, 10 of the 12 job openings at PA School District and most of the jobs at Clallam County were listed as open until filled (OUF), meaning that the first application that meets expectations will be chosen.

Part 7: Food Web Challenge

Complete the food web (untie the knot) challenge.

1. The teacher or designated student starts out as the "sun" and holds a spool of string, keeping the loose end in his/her hand.
2. Any student can raise her/his hand and be called on to share an organism that gets its energy from the sun and whether that organism is a "producer," "consumer," or "decomposer." E.g. "Grass, which is a producer, gets its energy from the sun."
3. Any student can raise her/his hand and be called on to share an organism that gets its energy from the organism just shared.
4. Once the energy gets to a decomposer, the next "producer" says where (s)he gets matter (not energy) from. E.g. "A blackberry, which is a producer, gets matter from a mushroom."
5. The string travels from person to person across the circle until it makes it to everyone (and then it returns to the first person).
6. Then, students try to untangle the web.

Part 8: Deadly Links

Play the Deadly Links game from Project Wild. Record data on the whiteboard.

Review the class Deadly Links Data.

After the game, answer the following questions in your journal:

1. How can toxic substances enter a food chain?
2. What impact can toxins have on organisms?
3. What happens to toxins as they move up the food chain?
4. What is another example of a food chain that is affected by toxins?
5. What is one way people can keep toxins out of the environment?

Food Webs Extension 1: Owl Pellet Dissection

An owl pellet is bones, hair, and other indigestible parts of an owl's prey that the owl regurgitates.

In your journal, write a hypothesis (prediction + reason) of what animals you think you'll find in the owl pellet.

Over a piece of black paper, dissect an owl pellet. Use the bone guide to identify animals, and tally the animals you found in the class data table.

After dissecting, answer the following questions in your journal as assigned.

Question List 1

1. What animals did the owl eat (support your answer with evidence from the pellet and information from the bone guide)?
2. Did the data support your hypothesis?
3. Was there anything in your data that surprised you?
4. If we were to do this lab with cougar scat, what do you think we would find?

Question List 2

1. What order consumer is the owl if it ate rodents?
2. What order consumer is the owl if it ate a bird or mole that ate an insect?
3. How much of the energy that was in the rodent became biomass in the owl?
4. What happened to the rest of the energy after the owl ate the rodent?

Share all your answers with another group, and then choose 1 key item from the other group's list to share out with class.

Food Webs Extension 2: Food Webs Large Poster

Create a large food web poster based on one of the National Parks in the textbook starting on p. 30.

Food Webs Extension 3: Wolves in the Olympics Persuasive Essay

Read the Orion Article on Wolves in Michigan. Watch the wolf predator-prey movie.

Wolves historically lived in the Olympic Mountains, but were all killed off (extirpated) in the 1920's.

Do you think wolves should be re-introduced to the Olympic Mountains?

Write a 5-paragraph persuasive essay on this topic.

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