Classroom Activity: The Web of Life

What plants and animals do you depend on for food? Explore the connections in wetlands and discover what can happen to the whole system when parts of it are changed.

| Materials | Preparation | Procedures | Evaluative Questions | Extensions | Sample Food Chain |

Objective:

Students will explore the connections between organisms in a wetland.

Concept:

All species in an ecosystem are interconnected; what affects one may affect others.

Time:

30 - 60 minutes.

Materials:

• 30 white card stock rectangles (3" x 8") for name tags
• four different colored balls of yarn

Preparation:

Make a set of cards with the following labels:

     Sun                     Bulrush             Snow Goose     

     Eagle                   Raccoon             Bacteria              

     Crawdad                 Mosquito            Dragonfly     

     Red-Winged Blackbird    Sandhill Crane      Marsh Grass

     Muskrat                 Cattail             Beaver

     Leopard Frog            Black Fly           Mule Deer

     Coyote                  Algae               Mallard Duck

     Mud Worm                Sandpiper           Cranefly

     Little Brown Bat        Water Moccasin      Maggot

     Fungus                  Earthworm

Make name tags by punching two holes in each card. Then loop a piece of yarn through the holes so that students can wear cards like a necklace.

Procedure:

1. Give one name tag to each student. Have everyone sit in a large circle so they can see each other's name tags. Explain to students that they will be using the yarn to trace the flow of energy and nutrients through an ecosystem by connecting the organism on their name tag to one that consumes that organism. These connections will be held as the game continues.
2. Using a ball of yarn, begin with the student who wears the "Sun" name tag. Ask him/her to hold onto one end of the yarn and roll the ball of yarn to a student wearing a plant name tag. Ask the "plant" student to hold onto the yarn and roll the ball to an animal he/she thinks eats plants. Discuss with the class whether this guess makes sense. Why or why not? Now have the "animal" student roll the ball to another animal he/she thinks is a predator. Eventually the group will run out of animals in this chain that eat each other. At this point the ball should be rolled to a decomposer to complete the chain.

Sample Food Chain

Sun .......Cattail .......Muskrat .......Marsh Hawk .......Maggot

3. Begin again with the "Sun," using a different colored ball of yarn. The group is making a series of food chains that together make up a food web. (See diagram.)
4. Continue until all students are a part of at least one food chain. Discuss the connections made by the yarn. What would happen if one type of animal (species) disappeared? How about a plant? Have one plant wiggle the yarn. How many animals in the web feel the vibration?

Evaluative Questions:

Can students name an organism that can safely be removed from the web without affecting any others?

What predictions can students make about effects on the food web of the events listed below?

• a virus kills all the waterfowl
• pollution kills all the decomposers
• poachers kill all the raccoons

Do certain species play a more important role in the wetland than others? Explain.

Extensions:

• Students can make up cards for a food web for one of the four wetland types from the next activity. (HINT: They'll need to do some research in the library for this one!)
• Record species seen during the Wild Wings: Heading South broadcast and make food chains and a food web using them.