Coral Reefs

Coral Polyps


Coral reefs are among the oldest and most diverse ecosystems on Earth. Learning about coral ecosystems encompasses many of the 9-12 grade science curriculum standards including life cycles of organisms, biological structure and function of organisms, and the behaviors and adaptations of organisms to their environment. All populations in this ecosystem are interdependent and part of a global food web.

Healthy coral ecosystems are important to humans, plants, fish, and other organisms that depend on them. However, changes in climate and human activities are endangering these ecosystems. Pollution, habitat loss, invasive species, and diseases are all threats to the survival of coral ecosystems around the globe. Learning about the fragility and value of coral ecosystems will help students understand what is needed to protect these resources.

Classroom Resources

These resources provide information, online data, and activities about the biology of the coral organism, types and distribution of coral; the populations, habitats, and dynamics of coral ecosystems; and the monitoring and conservation of coral ecosystems.

Teacher Tutorials

Cooperatively developed by NOAA scientists and National Science Teachers Association (NSTA) pedagogic experts, these tutorials are designed to help teachers understand a set of ideas based on the science literacy goals in the National Science Education Standards. Each tutorial focuses on a key content idea with interactive simulations and embedded questions.

The Living Reef

This tutorial presents the unique and diverse ecosystem of the coral reef. Coral reefs are complex systems that create some of the largest structures on Earth. Thousands of coral species exist in oceans worldwide. As they grow, reefs provide structural habitats for hundreds to thousands of different organisms.

Learning Outcomes:

  • Identify coral polyp structures and describe their functions.
  • Describe photosynthesis in the coral environment.
  • Describe the evolution of a typical reef system.
  • Use the shape of an individual coral to identify its common name, and classify entire coral reef ecosystems based on shape and location.
  • Describe the process of coral polyp reproduction and growth.
  • Identify how the features and/or behavioral strategies of coral reef inhabitants enable them to survive in coral reef environments.

The Abiotic Setting

This tutorial investigates the abiotic characteristics that affect coral reef ecosystems. The number and kinds of organisms found along each reef depend on the physical conditions of the environment and resources available, including food, light, water quality, temperature, and other organisms living in and around the reef. If conditions change significantly due to changes in climate, loss of food sources, excessive predation, or loss of habitat, the health and stability of the ecosystem will be affected.

Learning Outcomes:

  • Identify the characteristics of an ecosystem and describe the interdependence between biotic and abiotic features in an ecosystem.
  • Describe how the following abiotic factors provide corals with the energy needed to survive and grow within their ecosystem (sunlight, water, oxygen, and carbon dioxide).
  • Describe the optimal environmental conditions for coral reef growth and explain the process of coral reef development (including the role of available sunlight and calcium).
  • Explain how the following environmental factors might affect coral ecosystems: increases in dissolved carbon dioxide, changes in global temperatures, and increases in ocean water turbidity because of water pollution.


This tutorial explores the interdependent relationships between species in the coral reef ecosystem. All populations in the reef ecosystem are a part of and depend on a global food web through which energy flows in one direction, from the sun into each organism and eventually dissipating into the environment as heat. This food web includes ocean plants, the animals that feed on them, and the animals that feed on those animals. Energy is transferred between organisms and their environment along the way with energy concentration diminishing at each step. The cycles of life continue indefinitely because organisms decompose after death and return food materials to the environment.

Learning Outcomes:

  • Identify and label key components of food chains and food webs in a coral reef ecosystem.
  • Describe key relationships among plants and animals in the coral reef ecosystem including predator and prey relationships, producer and consumer relationships, and symbiotic relationships (mutualism, commensalism, and parasitism).
  • Recognize the direction that energy travels through food chains and food webs.
  • Explain that materials (e.g., chemical elements) and natural resources are recycled in coral reef ecosystems and reappear in different forms.
  • Describe the primary ecological succession events within a typical coral reef ecosystem.

Ecosystems in Crisis

This tutorial explores the natural and human causes of stress on coral reef ecosystems. Humans influence coral ecosystems in a variety of ways. Increasing amounts of stress are brought on these ecosystems as humans continue to modify the surrounding environment as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors are threatening the stability and overall health of many coral reefs. Human activities may also exacerbate the impact of natural disturbances on coral reefs or compromise the ability of the reef to recover from events such as hurricanes, tsunamis, or disease.

Learning Outcomes:

  • Describe ways in which human activities resource and recreational uses directly impact coral reef ecosystems.
  • Describe ways in which human activities indirectly impact coral reef ecosystems (e.g., by changing the physical conditions, pollution, or changes in the water chemistry).
  • Explain how human activity may decrease the ability of coral reefs to recover from natural occurrences.
  • Explain the effects of increased predation or disease on a reef ecosystem.
  • Describe the effect of habitat loss on the reef ecosystem.
  • Describe the effects of weather and climate change on a healthy or weakened reef ecosystem.

Web Seminar Archives

In collaboration with the NSTA, NOAA has presented a series of 90-minute, professional development experiences. Through the following links you can view archives of these Web seminars, download PowerPoint presentations, and access additional resources.

Coral Ecosystems I: Human and Natural Impacts and Coral Bleaching 101

These Web seminars focus on humans and natural impacts affecting coral reefs, such as pollution, disease, and invasive species. A primer on coral bleaching and what causes it is also presented, as well as the impact of hurricanes and wave action on reefs, how NOAA monitors coral bleaching, and what teachers and students can do to help coral reefs.

Coral Ecosystems II: Impacts to Coral Reefs and Land Based Pollution Threats

These Web seminars focus on how watersheds, animals, industry, environmental stress, and human recreation (e.g., diving, sailing, and boating) are impacting the health of coral reefs. Information on coral biology, the value of coral reefs, land-based pollution impacts, and management actions is also presented.



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