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A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. [1] Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and ...
The Amazon Reef (also referred to as the Amazonian Reef) is an extensive coral and sponge reef system, located off the coast of French Guiana and northern Brazil. It is one of the largest reef systems in the world known to exist, with scientists estimating its length to be over 600 miles (970 km) long, and covering over 3,600 square miles ...
It includes all of the stony corals, most of which are colonial and reef-forming, as well as all sea anemones, and zoanthids, arranged within five extant orders. [2] The hexacorallia are distinguished from another class of Anthozoa, Octocorallia , in having six or fewer axes of symmetry in their body structure; the tentacles are simple and ...
A variety of biotic reef types exists, including oyster reefs and sponge reefs, but the most massive and widely distributed are tropical coral reefs. [1] Although corals are major contributors to the framework and bulk material comprising a coral reef, the organisms most responsible for reef growth against the constant assault from ocean waves ...
Coral reefs are one of the most well-known marine ecosystems in the world, with the largest being the Great Barrier Reef. These reefs are composed of large coral colonies of a variety of species living together. The corals from multiple symbiotic relationships with the organisms around them. [21] Coral reefs are being heavily affected by global ...
Canton Island typifies the isolated coral atolls dotting the Pacific Ocean. The Structure and Distribution of Coral Reefs, Being the first part of the geology of the voyage of the Beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836, was published in 1842 as Charles Darwin's first monograph, and set out his theory of the formation of coral reefs and atolls.
The Great Barrier Reef is the world's largest coral reef system, [1] [2] composed of over 2,900 individual reefs [3] and 900 islands stretching for over 2,300 kilometres (1,400 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi).
Shallow water marine sediment primarily features larger grain sizes because smaller grains have washed out to deeper water. Within carbonaceous sedimentary rock, evaporite minerals such as gypsum, anhydrite, and halite may be present. [2] The most common evaporite minerals found within modern and ancient deposits are gypsum, anhydrite, and halite.