Coral Reefs


©Erin Burge

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Corals (Phylum Cnideria) are marine polyps that are in the same family as jellyfish and sea anemones. They typically live in colonies that grow and leave skeletal frames of calcium carbonate to create coral reefs, one of the most diverse ecosystems in the world that are considered “biodiversity hot-spots.” Thousands of species comprise this ecosystem representing all trophic levels from primary producers such as algae, to top level predators such as sharks.

The greatest threats affecting corals are human-related and include habitat degradation and exploitation by commercial industries. Corals are highly sensitive to the changes in pH, salinity, and temperature that result from climate disruption. Pollution leads to an accumulation of nutrients, called eutrophication, which promotes excess algal growth that can poison the animals. Agricultural and industrial run off increases sedimentation which clouds the water and reduces the ability of photosynthetic coral species to grow. The commercial trade of coral reef species results in the removal of species at an alarming rate, disrupting the ecosystem and reducing the health of reefs globally. Depending on their size, corals can take millions of years to grow back to their original size!

The AZA Aquatic Invertebrate Taxon Advisory Group and the AZA Coral Reef Conservation Action Partnership (CAP) works to conserve coral reef populations and help damaged corals recover. The Coral Reef CAP is developing a “Reef Medic” program with the National Oceanographic Atmospheric Administration and the Florida Keys National Marine Sanctuary to rebuild disappearing reefs. Additionally, the Coral Reef Task Force (CRTF) was established to map and monitor U.S. coral reefs, research the causes and effects of coral reef degradation, and promote the conservation and sustainable use of coral reef species.
The AZA Conservation Endowment Fund, and one of its sub-funds, the Disney’s Worldwide Conservation Fund, has provided over $83,000 in support of coral reef conservation projects including:

  • $21,130 to the New Jersey Academy for Aquatic Science to conduct population surveys of coral reef fish that may be threatened by commercial trade.
  • $21,400 to the Wildlife Conservation Society to conduct faunal surveys and develop a GIS database of Glover’s Reef Atoll in Belize.
  • $19,760 to the New York Aquarium for research on invertebrate-algal symbiosis and its implications for coral reefs.
  • $21,000 to the Florida Aquarium for the development of a Caribbean Coral Propagation Facility.
  • $20,000 to the Waikiki Aquarium for the development of an in ex-situ coral propagation program.

Coral Reef Facts

Status Corals create a reef that supports several endangered and threatened species.
Size The size of the reef varies based on the age of the community.
Appearance There are many different kinds of corals.  Corals are primarily either hard or soft, and some even look like plants! Their bodies are in the form of a polyp, with tentacles at the upper end, and attached to the surface at its base. The tentacles carry stinging (nematocyst) cells.
Habitat Corals live in clear, shallow, tropical waters.
Diet Corals eat animals called zooplankton (tiny animals) and sometimes small fish, depending on the size of the coral polyps.  They use their stinging tentacles to stun their prey.  Some corals are photosynthetic.
Breeding Spawning occurs as a mass synchronized event, when all the coral species in an area release their eggs and sperm at about the same time. The timing of a broadcast spawning event is very important because males and female corals cannot move to be near each other.