Food Webs
Click here to download & print the Reef Food Web Diagram in Adobe Acrobat format.*

Objectives

  • create an ocean food chain
  • make a food chain and food web display

 

Vocabulary

  • photosynthesis
  • producer
  • herbivore
  • carnivore
  • scavenger

 

Background

In the sea as on land, plants capture and store the energy of the sun through the process of photosynthesis. Seaweeds, turtle grass and tiny floating plants, called phytoplankton, are the food producers on the reef. Herbivores, like sea urchins and sea turtles, are animals that eat the plants. Sharks, dolphins and barracuda are carnivores, animals that eat the herbivores and other carnivores. Scavengers, like spiny lobsters, are garbage collectors. They eat the leftovers and clean up when other organisms die.

Scientists study the hunters and the hunted and develop food chains to show who eats whom. Connections between food chains make a food web.

 

Materials

  • drawing paper and crayons
  • photographs of reef animals
  • balls of colored yarn
  • reference books
  • Reef Food Web Diagram (download*)

 

Activity

Discuss the various levels in a food chain, from producer to top-level predator. The Reef Food Web Diagram gives examples of several food chains that the SFS students at the South Caicos research site may observe on the reef.

Now, divide students into food chain research teams and complete the following steps. If there is only one student, have him/her repeat these steps for two or three different producers and carnivores.

  1. Give each student or team the name of a producer and a second level carnivore. Have them answer the following: What animals would eat this producer? What animals would this carnivore eat? Have each team research two food chains, one for the producer and one for the carnivore.
  2. Ask students to illustrate their food chains. For example:

(producer)è (herbivore)è (1st level carnivore)è (2nd level carnivore)

sea lettuceè sea urchinè angelfishè shark

  1. Have students draw or find photographs to illustrate each link in the chains.
  2. Have students create a bulletin board display as follows: (a) Put all of the producers along the bottom, the predators at the top, and the herbivores in the middle of the board. If the same animal or plant is used more than once, group the illustrations together at a single food "station." (b) Using different colors of yarn, have students connect the plants and animals within each food chain. (c) As students work, discuss any food webs that appear. Can students identify other possible connections?

 

Extend the Activity

  • Have students stand in a circle. Give each student an identification badge with the name and/or picture of a reef plant or animal. Have students identify the producers, herbivores and carnivores. To start the game, give one of the producers a ball of string and ask them to hold onto the loose end. Then ask an herbivore to walk across the circle, take the ball of string from the producer and slowly unwind it as he/she returns to his/her place in the circle. Next a carnivore should take the ball from the herbivore and so on. When the first food chain is complete, give a different colored ball of yarn to the next producer in the circle and repeat the steps to create a second food chain. Hint: Be sure to have an herbivore for every producer in the circle, and include both small and large carnivores.
  • Research and display food webs for other ocean environments: a salt marsh, a tide pool, a polar sea (and remember, polar bears don’t eat penguins—one lives in the northern hemisphere, the other in the southern hemisphere).
  • Humans are at the top of the food chain. Keep a journal of what you eat for one day. Draw some food chains or food webs with you at the top.

 

* If you do not have Adobe Acrobat Reader, download it for free from www.adobe.com