Lesson Plan

Coral Reef Ecosystems


In this lesson, students apply their understanding of ecosystems to the study of coral reef ecosystems in particular. Students will examine the effects of human actions on coral reefs. Students will:

  • explain why biodiversity in coral reefs is important to the health of the ecosystems.
  • trace the flow of energy through coral reef ecosystems.
  • identify relationships among organisms in coral reef ecosystems.
  • explain how human activities may affect coral reefs and describe the response of coral reef organisms to environmental changes.

Essential Questions


  • Symbiosis: A relationship in which two species live closely together.
  • Coral Polyp: An individual coral organism in a coral reef.
  • Coral Reef: An ecosystem found in shallow tropical marine waters around the world; home to over 100,000 species of marine organisms.
  • Biodiversity: The sum total of different species of organisms in an ecosystem.
  • Bleaching: A stress response of coral reefs to changes in the environment, such as warming ocean temperatures; coral loses its algae and turns white.


45–90 minutes/1–2 class periods

Prerequisite Skills

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Related Materials & Resources

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Formative Assessment

  • View
    • Orally assess students’ understanding of concepts from the previous lessons in this unit during the discussions of symbiosis and the relationships and energy flow in coral reef ecosystems.
    • If you do the Internet activities, circulate around the room and ask relevant questions to assess understanding.
    • Collect written answers to the “Energy Flow in the Coral Reef Ecosystem” Web site discussion questions.
    • Collect and check the Human Threats to Coral Reef Ecosystems handout for individual assessment.

Suggested Instructional Supports

  • View
    Scaffolding, Active Engagement, Modeling, Explicit Instruction
    W: This lesson synthesizes concepts on ecological relationships from the previous two lessons, and applies them to a specific ecosystem. Also, the lesson provides data on human effects on coral reefs.
    H: The lesson begins by having students apply prior knowledge of types of symbiosis to identify specific symbiotic relationships in coral reefs.
    E: Students identify relationships among coral reef organisms, and explain the flow of energy in coral reef ecosystems. Then, they analyze data to explain the effects of human actions on coral reefs.
    R: Students revisit concepts from the previous two lessons throughout this lesson. The analysis questions on the handout ask students to consider the importance of coral reef ecosystems.
    E: Students are evaluated orally throughout the lesson, and the handout will be collected and checked.
    T: This lesson can be modified by providing reinforcement of concepts during the food web discussion. It can be extended by having students further explore data on human affects on coral reefs. Also, the Related Resources for this lesson offer many additional opportunities for additional practice and instruction on coral reef ecosystems.
    O: The lesson begins with having students apply their understanding of how ecosystems function to the coral reef ecosystem in particular. Then, students analyze data to assess human impact on coral reef ecosystems.

Instructional Procedures

  • View

    Review the definition of symbiosis from Lesson 2, and read the following description to students, asking them to try to determine which kind of symbiosis it is: “All corals are animals, but like lichens on land, which are part fungi and part algae, they have a symbiotic relationship with algae. Most corals contain symbiotic algae called zooxanthellae (note: pronounced zo-zan-thel-ee), within their tissues. The coral provides the algae with protection and the compounds it needs to carry out photosynthesis. In return, the zooxanthellae are the corals’ ‘solar panels,’ providing the reef building corals with enough energy to extract calcium from the seawater to build their skeletons quickly. The zooxanthellae use sunlight for photosynthesis and produce oxygen and sugars which the corals can use. This symbiosis is so successful that fast-growing species of corals can grow up to 20 cm (8 inches) per year. What kind of symbiosis is this?”

    Elicit from students that this is mutualism, a relationship in which both organisms benefit. (It may be helpful to provide choices: mutualism, amensalism, parasitism, and commensalism.)

    Tell students, “Many other coral reef animals, including sea anemones, soft corals, and giant clams, also have symbiotic relationships with these algae and with each other.” Provide an example of a coral reef food chain or food web (S-8-9-3_Coral Reef Food Web.doc). Have students identify relationships among organisms in the coral reef ecosystem. Also, have students describe the flow of energy through the coral reef ecosystem.

    If computers with Internet access are available and time permits, have students view the video clip at the “Energy Flow in the Coral Reef Ecosystem” Web site and write answers for the “Discussion Questions,” and/or do the interactive coral reef activity at the “Coral Reef Connections: Great Barrier Reef” Web site at www.pbs.org/wgbh/evolution/survival/coral/index.html.

    Provide students with instruction on coral reefs, including what they are, their importance, and the impact of humans on them. Display the outline on Coral Reef Ecosystems (S-8-9-3_Coral Reef Outline.doc). Have students copy the outline into their notes.

    Display the Coral Reef Locations Map (S-8-9-3_Coral Reef Locations Map.doc) and explain why coral reefs are found in tropical locations (i.e., they need sunlight for photosynthesis and warm water for the survival of organisms).

    Hand out the Human Threats to Coral Reef Ecosystems–Student Version (S-8-9-3_Human Threats to Coral Reef Ecosystems-Student Version.doc and S-8-9-3_Human Threats to Coral Reef Ecosystems-Teacher Version.doc). Have students examine the data and answer the Analysis Questions.


    • Students who might need an opportunity for additional learning can use a copy of the Coral Reef Food Web (S-8-9-3_Coral Reef Food Web.doc). Have them review vocabulary from this unit by identifying: producers, consumers, herbivores, carnivores, omnivores, and trophic levels. Have them describe the flow of energy through one food chain in the web.
    • Students who may be going beyond the standards can design a 2–3 minute public service announcement (for television or radio) to improve understanding of human threats to coral reefs, and actions we can take to protect coral reef ecosystems. The Save a Reef Web site may be useful for this extension (see Related Resources).

Related Instructional Videos

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DRAFT 05/16/2011
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