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Food Web

QCC Correlations

Science Standards 4.1, 4.23, 4.24, 7.1, 7.19

Objectives

The Students will be able to:

  • Define food web
  • Identify the interdependence of organisms within a system
  • Describe how natural events and human activities can impact a food web
Materials Needed:
  • Access to Eye on Conservation and Georgia Wildlife Web sites
  • Pictures of the animals highlighted on the Eye on Conservation web site
  • Ball of yarn
  • Index cards (5x7) or paper (8 ½ x 11)
Procedure:

1) Prepare some food web cards and laminate them ahead of time by writing the name of each element of a food web on a card. If available, glue a picture of the element onto the card as well. Attach a string to each end of the card so the students can wear the cards around their necks.

2) The longleaf pine habitat found on the coastal plain of Georgia is a good system to use in this activity. Many of the species found on the Eye on Conservation web site live in this community. About 97% of this habitat has been destroyed and consequently many of the plants and animals that live there are endangered. For more information on the Longleaf pine ecosystem visit: http://www.consci.org/eglin/
http://www.fws.gov/southeast/mountainlongleaf/longleafpine.html
http://carolinasandhills.fws.gov/longleaf.html

3) Be sure to include all of the following elements of the food web:

  • Sun
  • Five plants (see below)
  • Five insects/spiders - butterfly, black widow spider, beetle, bee, wasp, ant
  • Three reptiles or amphibians (see below)
  • Two raptors (see below)
  • Three other birds (see below)
  • Three herbivorous mammals (see below)
  • Three carnivorous mammals (see below)
  • Three decomposers - fungi, earthworm, dung beetle
  • Non-living components of the food web - water, air, soil
  • Longleaf pine food web:
    • Plant examples include longleaf pine, prickly pear cacti, wire grass
    • Reptile and amphibian examples include the gopher frog, the gopher tortoise, indigo snake, flatwoods salamander, marbled salamander, black racer and diamond back rattlesnake.
    • Raptor examples include turkey vulture and red tailed hawk
      Other birds include the red-cockaded woodpecker, pine warbler, bob-white quail, pine woods sparrow, and brown-headed nuthatch
    • Herbivore examples include the southeastern pocket gopher, southern flying squirrel, Florida mouse, white-tailed deer, and fox squirrel
    • Carnivore examples include the bobcat, gray fox, and Florida panther (now extinct in Georgia)

Another good food web to demonstrate is the ocean. In this system you could include the northern right whale, manatee, and leatherback sea turtle.

4) Discuss food webs with the kids. Include the roles of producers, consumers, and decomposers. The entire web begins with the sun. Plants use the suns energy to produce energy for themselves through photosynthesis. Primary consumers (herbivores) eat the plants. Secondary consumers (carnivores) eat the herbivores. Tertiary consumers (carnivores) are the top predators of the system. Decomposers break down the plants and animals after they have died and the nutrients are returned to the system.

5) Pass out the food web cards to each kid. You can do this activity in one large group or in several small groups. If you chose to do it in small groups, break the class up.

6) Have the students arrange themselves in a circle. The person who has the sun card starts. The sun holds the end of the ball of yarn and throws or rolls it to someone else in the circle, explaining his or her connection to the next element. For example, "The sun gives energy to the longleaf pine tree." The next person holds onto the yarn and throws the ball, explaining the connection. The explanations can be based on predator/prey relationships, for example, the hawk eats the mouse, or on other relationships. For example, the woodpecker lives in the longleaf pine or the mouse lives in the tortoise burrow. Each time the ball is thrown, the individual throwing it holds onto his or her end, so that a web is formed by the yarn in the center of the circle. This goes on until everyone holds a piece of yarn. The yarn must be held taut in order to illustrate the interconnectedness of all the elements.

7) Ask the kids what they think would happen if something happened to one of the elements in the web. Now demonstrate. Point to one individual and announce that this organism is killed either by a natural (ex. Large storm or disease) or human cause (pollution or habitat loss). As that plant or animal drops out of the food web and lets go of the yarn, each person who feels the slack of the yarn lets go. Soon, the entire web has fallen to the ground all because one member of the food web was killed.

8) You may wish to play the game multiple times. The activity will be different each time because animals and plants interact in many different ways.

9) Discuss the activity with your students. Ask them what they think would happen if more than one organism in the food web was killed. Conversely, what if the population of one animal increased suddenly? What if there were too many carnivores and few herbivores? Or, if there were too few carnivores and too many herbivores? What would happen to the food web?

Source: Adapted from Animal Tracks: Habitat Activity pack, National Wildlife Federation