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What you will do Portray members of a food chain and track energy loss from the ecosystem

Earth Science

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What you will do

• Portray members of a food chain and track energy loss from the ecosystem.
• Illustrate the effects of biological magnification by passing a "toxin" through the food chain.

What you will need

Plastic poker chips, coins, cardboard cutouts, etc. (anything to represent "energy" and "toxins" in an ecosystem) 
Plastic sandwich bag
Paper or chalkboard on which to record data 

How you will do it

1. Stand with the other members of your assigned trophic group. As a class, discuss why there are so many herbivores, but so few quaternary consumers.
2. Spread out the "energy chips" on the floor; count and record the initial number of chips. These chips represent the energy that the ecosystem's plants have produced. Plants are able to produce energy by harnessing the energy of the sun, although most of the sun's energy is never captured.
3. Herbivores: Move about the area where the energy chips are located. You need to collect four energy chips and place them in your plastic bag. These chips represent the energy that the herbivores obtain when they consume plants. Record the total number of energy chips captured by the herbivores.
4. Secondary consumers: Enter the ecosystem and "tag" a herbivore. This tag represents the herbivore's death and the transfer of energy from the herbivore to the carnivore. There is energy loss associated with this transfer, however, so you can only obtain, at most, three energy chips from the herbivore. If you are a tagged herbivore, give three of your energy chips to the carnivore (secondary consumer). If you are a carnivore, place these chips in your bag. Each secondary consumer may eat up to three herbivores. Record the total number of energy chips held by this level of the ecosystem (secondary consumers), once the predation cycle is complete.
5. Tertiary consumers: "Eat" the secondary consumers. However, you can obtain only two energy chips from each secondary consumer. Each tertiary consumer can eat two secondary consumers. Record the total number of energy chips at this level, once predation has ended.
6. Quaternary consumer(s): Eat the tertiary consumers and obtain one energy chip from each tertiary consumer. Record the number of energy chips at this level.
7. Now examine the data. As a class, explain why all of the energy was not transferred from one level to the next, when an organism was eaten. In addition, explain why so many herbivores, but so few quaternary consumers, existed in this ecosystem.
8. Return all of the chips to the floor. The chips no longer represent energy, but rather a toxin (e.g., DDT) that was sprayed in the ecosystem. As a class, hypothesize what will happen: Will the toxin get more dilute as it moves up the food chain, or will it become more concentrated?
9. Herbivores: Begin picking up chips, as before (Step #3), but remember that the chips now represent toxin exposure and not energy. Record the number of toxins per organism.
10. Secondary consumers: Enter the ecosystem and "consume" three herbivores. Now, the herbivores must give you all of their toxin chips. All of the toxin chips are transferred, unlike the energy chips, because some toxins exhibit the tendency to remain in an ecosystem, rather than being lost. Record the number of toxins per organism.
11. Tertiary consumers: Eat two secondary consumers. Each must give you all of their toxin chips. Record the number of toxins per organism.
12. Quaternary consumer(s): Eat the tertiary consumers and acquire their toxin chips.
13. Take a picture of your game pieces and data.   Analyze the data and explain why the food chain contributes to the phenomenon of biological magnification.

Open a new document. Insert the picture you took in #13 of your game pieces and data you recorded. paragraph description of the activity, including your thoughts and questions. Than answer the following 6 questions.

• Where is energy lost in a food chain?
• What are the effects of toxins in a food chain?
• Are higher levels of the food chain affected more or less? Why? Explain your answer in detail.
• Define biomagnification.
• Explain why the food chain contributes to the phenomenon of biological magnification.
• Give a real life example of biomagnification (this may take some extra research on your part.