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Coral reef

noun, plural: corals
(marine biology) A type of biotic reef comprised primarily of coral skeletons and algal endosymbionts
A coral reef is one of the different types of biotic reefs. As the name implies, a coral reef is one that which is comprised of coral skeletons (especially the stony corals). However, another major component of this structure is endosymbiotic algae, especially zooxanthellae and coralline algal species.
The coral component comes from the coral polyps that are connected to one another forming a colony. The coral polyps obtain calcium and carbonate ions from the seawater. They then secrete them as calcium carbonate (limestone) in order to build a hard skeleton. This skeleton is essential to the coral polyps because it provides protection since their body is soft and delicate. The coral reefs may appear in brilliant colors. This is because of their symbiotic relationship with endosymbiotic algal species such as zooxanthellae and coralline algae. Apart from the coral polyps and the zooxanthellae, the coral reef may also have other components such as seaweed, sponges, sediments, etc.
The coral reefs are an important marine structure because they provide an underwater ecosystem for various small marine animals. The three major types of coral reefs are fringing reef, barrier reef, and atoll reef.
Word origin: French corail, from Latin corallium, from Ancient Greek korállion (“coral”) + reef
Scientific classification:

  • Kingdom: Animalia
  • Phylum: Cnidaria
  • Class: Anthozoa Ehrenberg, 1831

See also:

  • Anthozoa
  • coral
  • zooxanthella