Lesson 2: Who's Eating Whom?

Explain the Rules

1. Each student represents a producer or a consumer. Consumers will play the role of predators, prey, or both.
2. Each producer has 30 green food tokens, representing 30 individual marsh plants of the same species.
3. Each primary consumer (macroinvertebrates, snails, clams) starts with 10 food tokens; secondary consumers (crayfish, frogs, small fish, bluegill) start with 5 food tokens, and top predators begin with only one red token. Each token represents an individual organism of the same species.
4. During the first cycle, or year, each consumer will need to eat enough food to survive and grow and thus to reproduce. Consumers collect tokens by identifying the feeding behaviors of their prey and then tagging them. When someone is tagged they have to give up a token. Each food token a consumer consumes will represent a new organism of the consumer species.
5. People, raccoons, blue herons, pike and bass are at the top of the food web and must consume 10 organisms to survive.
6. Bluegill, small fish, crayfish, and frogs are secondary consumers (which may be predators or prey). They will need to consume and have in possession five organisms at the end of the year in order to survive. However, they must also avoid predation. If captured, they must give up one token.
7. Clams, snails, and macro-invertebrates (primary consumers) need only to end the year with one organism to survive. However, they must also eat enough to account for predation or they will die, too.
8. Plants can die, and they are directly returned to the system as nutrients; therefore, plants need nothing to eat, but if these students are out of tokens then they must wait until another organism dies due to lack of food (i.e, a student is eliminated after losing all tokens) and returns enough nutrients to the ground to create new plant growth.
9. Any organism that does not end the year with enough tokens to survive will return what they do have to the ground for consumption by plants and other organisms that feed on decaying organisms.
10. It is important that each organism continues to act out what it is. If an organism forgets what different pantomimes represent, then it is up to them to investigate, if they want to survive. However, they will have to realize that food webs are not forgiving, and a nosey little fish that investigates a pike will become food for a pike!

Play the Game

1. Establish a play area (inside a classroom or outside) and have all producers take their envelopes with them, spread out on the playing field, and start acting out their roles.
2. Next, tell everyone else to begin to pantomime their respective behaviors, capture their prey by tagging others, and secure a food token from them, placing it in their envelope.
3. End the game after most top predators have gotten 10 food tokens.
4. Tell the students to hold onto their food envelopes so that they can participate in class discussion.

Discuss the Results

1. Did every top predator “fill up” by getting 10 food tokens during the cycle or year? If not, why not? (Some animals are more selective in feeding preferences and therefore may have a more difficult time finding food.) Talk about the different way the animals are connected to each other and the producers. Be sure that the supporting roles of decomposers do not get overlooked. Decomposers are responsible for breaking down dead organisms into nutrients usable by plants for growth.
2. Draw a food web based on what feeding interactions took place during the game. Discuss the path that some tokens took to get from the bottom of the web to the very top. Discuss how many plants and lower organisms it took to support the top of the food web.
3. Optional: Replay the simulation for a second round or year, leaving the tokens distributed as they were after the first round. Tokens left over from an organism that died during the first year will be returned to the ground for consumption by organisms such as the plants and crayfish.
4. Summarize by emphasizing the importance of freshwater marshes. These marshes provide habitat for a variety of different kinds of animals.

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