Not a fact anymore

A coral reef is a solid mass of living coral.

What we know now

Only a thin outer layer of a coral colony is living tissue. Reef frameworks contain accumulated calcium-carbonate skeletons, dead coral, sediments, algae, sponges, microbes, and many other organisms.

Why it changed

The visible reef surface is colorful and alive, making the whole structure seem like one living mass. Drilling, cores, anatomy, and ecology revealed layered skeletons and sediments beneath the living veneer.

Status
Corrected
Category
Ocean Science
Accepted for
≈42 years
Accepted approximately
Common early natural-history and public model
Changed approximately
19th–20th centuries

A reef is still a living ecosystem, even though much of its physical framework is nonliving skeleton.

Different reefs contain different proportions of coral, algae, sediment, and other builders.

Evidence

Sources and what they establish

Current evidence

  • What is a coral reef made of?NOAA National Ocean Service

    Explains that coral polyps form a living mat over a calcium-carbonate skeleton.

  • Coral ReefsFlorida Keys National Marine Sanctuary

    Describes a coral colony as a hard skeleton covered by a thin veneer of living tissue.

Historical context

Related entries

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