Who Eats Whom? (PCEC)

Summary:

Develop a food web using yarn and nametags. This shows how one environmental factor can affect many others.

Grade Level:

4 or higher

Recommended Setting:

Indoor or outdoor classroom

Outdoor Activity:

No

Location:

Potlatch Conservation Education Center at Cook’s Lake, Casscoe

Contact:

Education Program Coordinator, 870-241-3373

Duration:

30 minutes

Suggested Number of Participants:

20 - 25

Special Conditions:

One adult supervisor per 10 students; outdoor activities, weather-permitting.

Objectives:

  • Understand that connected, interrelated food chains compose a food web.
  • Demonstrate various paths of energy flow from one organism to another.
  • Identify organisms that occur throughout the food web as decomposers, producers or consumers.
  • Create a written and/or visual scenario predicting sequences of change within a food web when species are lost.

Key Terms*:

Carnivore

Consumer

Decomposer

Food chain

Food web

Fungus

Herbivore

Omnivore

Predator

Prey

Producer

Scavenger

*See glossary for definations

Materials:

Cook’s Lake habitat descriptions

Markers

Nametags

Yarn

Background:

A food chain shows how energy can be passed from one organism to another. Food chains may be simple or become complex as more parts are added. A food web shows the interactions between all parts of a food chain.

Procedure:

  1. Choose an area of Cook’s Lake that can be used to design a food web: deep woods, clearing, marsh, fast stream, pond. Use the Cook’s Lake habitat handout descriptions if necessary.
  2. Have each participant choose from the following groups an organism to role-play—plant, animal, protist, bacteria or fungus. After selecting an organism, each person should make a nametag with the picture and name of the organism. Participants will hang the nametag around their necks or tape it to their chests. These may be prepared and laminated ahead of time.
  3. Tell participants they will construct a food web using yarn to simulate the interaction of the organisms. Hand one of the participants a ball of yarn and have him/her toss it to one of the organisms he/she can eat or something that can eat him/her. Help participants decide who is their predator or prey if necessary. Continue until there is a fairly complex crisscross of yarn.
  4. Discuss the following:
    • Most organisms eat more than one thing
    • Most organisms can be labeled as carnivores, herbivores, omnivores, scavengers, or decomposers
  5. To make the simulation work, be sure to have some of each kind of organism in the web (producer, carnivore, herbivore, scavenger, decomposer).
  6. Ask all the predators to pull tightly on their strands. Does anyone besides the prey feel the tug? Why or why not?
  7. Ask all producers to drop their strands to the ground. What happens to the web?
  8. Discuss the interdependence of organisms and their nutritional relationships.
  9. Design a food web for a different Cook’s Lake habitat. Help participants to understand that different food webs exist for different habitats.
  10. Ask if food webs in different habitats are independent of one another.
  11. Discuss the fact that many organisms move from one area to another—deer move from woods to meadow, seeds blow from one area to another. Discuss the fact that all of earth’s food webs are connected.

Modifications:

  • Write a story about any habitat you choose and the relationships that exist among the organisms that live there.
  • Design a food web from a list of animals such as the following:
    • Blue jay
    • Camel
    • Cobra
    • Cricket
    • Eagle
    • Elephant
    • Fox
    • Frog
    • Garter snake
    • Hawk lily pad
    • Kangaroo lion perch
    • Robin
    • Salamander
    • Skunk

Review:

  • What is the difference between a producer and a consumer?
  • What is the difference between a predator and a prey?
  • Why are decomposers so important? What is the role of a scavenger? The fungus?
  • Create a food web in which humans are included.
  • Describe how all parts of a food web can be interrelated.

Glossary:

Carnivore – any animal that consumes other animals that are living (predation) or dead (scavenging)

Consumer – in ecology, organism, usually an animal, that feeds on other organisms and their remains; classified as primary consumers (herbivores), secondary consumers (carnivores) and microconsumers (decomposers)

Decomposer – an organism that breaks down large chemicals from dead organisms into small chemicals and returns important materials to the soil and water

Food chain – feeding order in an ecological community that passes food energy from one organism to another as each consumes a lower member and in turn is preyed upon by a higher member

Food web – a network of interrelated food chains in an ecosystem

Fungus – small, often microscopic, organism that lacks chlorophyll and cellulose in its cell walls

Herbivore – a plant-eating animal

Omnivore – an animal that eats both animal and vegetable matter

Predator – an animal that hunts and kills other animals, usually for food

Prey – an animal that is killed and eaten by another animal

Producer – organism that creates its own food from inorganic substances through photosynthesis (by green plants) or chemosynthesis (by anaerobic bacteria) and serves as a source of food in the food chain

Scavenger – animal, such as a bird or insect, that feeds on decaying matter