How would you describe a marine food web? What would be in it?

In the Film

Cool water and an abundance of plankton in the Gulf of California contribute to the formation of an ocean oasis. The concentration of life around some of the reefs is compared to a city—with opportunities, risks, and competition. Various organisms of the community are shown feeding upon other members of the community, creating a marine food web.

Concept

Organisms interact with one another in various ways.

Objective

To construct a food web representative of the Gulf of California

Content

Science, language arts

Background

The interactions of organisms with other organisms and with their physical environment form the basis of the study of ecology. Food chains and webs are often used to portray these interactions. Plants (producers) use sunlight and inorganic materials to produce the organic compounds that become food and nutrients for other organisms—the consumers. Those animals that feed upon plants are called primary consumers, while animals that eat other animals are secondary or even tertiary consumers. Scavengers feed on dead organisms, while decomposers break down nonliving organic matter into materials that again are available to enter the food chain as nutrients. Nutrients of the marine ecosystem tend to settle to the bottom. Upwelling of cool water brings the nutrients closer to the surface where they are available to phytoplankton (very small plants drifting in the sea). The phytoplankton, in turn, become food for zooplankton (very small ocean animals) and larger organisms. Mysids (tiny shrimp), barnacles, fish, sponges, sharks, dolphins, and sea birds are just some of the many animals seen in Ocean Oasis.

On the Web

The Ocean Oasis Field Guide has pages about each of the species mentioned in this activity. For more on sharks, see Shark School, part of Kids' Habitat on the San Diego Natural History Museum website. For reptiles and amphibians, see the SDNHM Field Guide. Activity 6 demonstrates upwelling.

Pictures below, art supplies, paper, glue, scissors, resource materials

(individuals, small groups)

• Discuss the basic concept of food chains and food webs, including nutrients, sun, oxygen, carbon dioxide, decomposers, producers, and consumers at different levels.
• Use pictures below to create a marine food web. Be sure to put organisms in the appropriate level of the web—producer, primary consumer (level 1), secondary consumer (level 2), etc. Put the phytoplankton near the surface, draw the sun above the water, and show bacteria, dead organisms, and nutrients on the ocean floor.
• Challenge—connect various organisms with arrows to show food chains within the web.
• Would humans fit in the food web? Where?
• Where are the nutrients? How do they reach the surface?
• What would happen to the web if one or more organisms were removed?
• Which level in the web do you think is most important? Why?
• To learn more about the organisms in your food web, click on the drawings below.

Local Connection

• Think of wild animals that live near you. Use sketches or pictures of these animals and other appropriate organisms to create a terrestrial (land) food web. Even urban areas have wild organisms (e.g., birds, rats, mice, snails, insects, and plants) that may be used to create a food web.
• Compare the marine and terrestrial webs. How are they alike? How are they different?

Continue to Activity 11: Marine Matchmakers