Corallite

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Diagram showing a coral polyp, its corallite, coenosarc and coenosteum Coral polyp.jpg
Diagram showing a coral polyp, its corallite, coenosarc and coenosteum
Up : zoom on the skeletal cup of an Astrangia coral; Down : view of the skeleton of the whole colony, showing all the coralittes. Astrangia danae.jpeg
Up : zoom on the skeletal cup of an Astrangia coral; Down : view of the skeleton of the whole colony, showing all the coralittes.

A corallite is the skeletal cup, formed by an individual stony coral polyp, in which the polyp sits and into which it can retract. The cup is composed of aragonite, a crystalline form of calcium carbonate, and is secreted by the polyp. Corallites vary in size, but in most colonial corals they are less than 3 mm (0.12 in) in diameter. [1] The inner surface of the corallite is known as the calyx. The vertical blades inside the calyx are known as septa and in some species, these ridges continue outside the corallite wall as costae. [2] Where there is no corallite wall, the blades are known as septocostae. The septa, costae and septocostae may have ornamentation in the form of teeth and may be thick, thin or variable in size. Sometimes there are paliform lobes, in the form of rods or blades, rising from the inner margins of the septa. These may form a neat circle called the paliform crown. The septa do not usually unite in the centre of the corallite, instead they form a columella, a tangled mass of intertwined septa, or a dome-shaped or pillar-like projection. In the living coral, the lower part of the polyp is in intimate contact with the corallite, and has radial mesenteries between the septa which increase the surface area of the body cavity and aid digestion. The septa, palliform lobes and costae can often be seen through the coenosarc, the layer of living tissue that covers the coenosteum, the part of the skeleton between the corallites. [3] [4]

In colonial species, when the corallites each have a surrounding wall, the colony is said to be plocoid. When the walls are tall and tubular, the colony is phaceloid, and when several polyps share a common wall, the colony is cerioid. Sometimes the polyps are in valleys on the surface of solid corals, they are then known as meandroid. [5] Branching corals have two forms of corallites, axial and radial. The axial corallites tend to be shallow and are found near the tips of the branches while the radial corallites are on the sides of the branches. Corallites can be rounded or polygonal and may be inclined (tilted obliquely to one side). [3]

As long as the colony is alive, the polyps and coenosarc deposit further calcium carbonate under the coenosarc, thus deepening the corallites. Each polyp has a fixed adult size and, when it is beginning to get submerged in the corallite, it secretes a new floor (tabula) beneath itself. Over time, a series of floors builds up below the living polyps, resulting in a thickening and lateral expansion of the coral. [1]

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<i>Pavona duerdeni</i>

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<i>Lobactis</i>

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<i>Eusmilia</i>

Eusmilia is a genus of stony coral in the family Meandrinidae. It is a monotypic genus represented by the species Eusmilia fastigiata, commonly known as the smooth flower coral. It is found on reefs in the Caribbean Sea.

<i>Pseudodiploria clivosa</i>

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<i>Acropora secale</i>

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<i>Lobophyllia corymbosa</i>

Lobophyllia corymbosa, also known as lobed cactus coral or brain root coral, is a species of large polyp stony coral in the family Lobophylliidae. It occurs on reefs in shallow waters in the Red Sea, off the coast of East Africa, and in other parts of the tropical Indo-Pacific.

<i>Acropora loripes</i>

Acropora loripes is a species of branching colonial stony coral. It is common on reefs, upper reef slopes and reef flats in the tropical Indo-Pacific. Its type locality is the Great Barrier Reef.

<i>Cynarina lacrymalis</i>

Cynarina lacrymalis is a species of stony coral in the family Lobophylliidae. It is variously known as the flat cup coral, solitary cup coral, button coral, doughnut coral, or cat's eye coral. It is found in the western Indo-Pacific Ocean and is sometimes kept in reef aquaria.

<i>Dipsastraea speciosa</i>

Dipsastraea speciosa is a species of colonial stony coral in the family Merulinidae. It is found in tropical waters of the Indian and Pacific oceans.

Astrangia solitaria, the dwarf cup coral or southern cup coral, is a species of stony coral in the family Rhizangiidae. It is native to shallow water in the western Atlantic Ocean and the Caribbean Sea.

In corals, the coenosteum is the stony skeletal material secreted by the coenosarc, the layer of living material lying between the corallites. The coenosteum is composed of aragonite, a crystalline form of calcium carbonate, and is generally a spongy, porous material. Sometimes the coenosteum has ornamentation such as ridges and beads, visible as raised areas of the coenosarc. The coenosteum and corallites together are known as the corallum.

<i>Favites pentagona</i> Species of stony coral in the family Merulinidae

Favites pentagona is a species of stony coral in the family Merulinidae, sometimes known as larger star coral. It is native to the Indo-Pacific region and its range extends from the Red Sea through the Indian Ocean to the Western Pacific Ocean. This is a common species throughout its wide range and the International Union for Conservation of Nature has rated its conservation status as being of "least concern".

<i>Madracis auretenra</i>

Madracis auretenra, commonly known as the yellow finger coral or yellow pencil coral, is a colonial species of stony coral in the family Pocilloporidae. It is a fairly common species and is found in the Caribbean Sea and western Atlantic Ocean. At one time this species was not recognised, but it was split from Madracis mirabilis on the grounds of morphology and depth range.

<i>Dactylotrochus</i>

Dactylotrochus is a genus of large polyp stony corals from the Red Sea and western Pacific Ocean. It is monotypic with a single species, Dactylotrochus cervicornis. It inhabits the deep sea and is believed to be azooxanthellate.

<i>Favites complanata</i>

Favites complanata is a species of stony coral in the family Merulinidae, sometimes known as the larger star coral. It is native to the Indo-Pacific region and its range extends from the Red Sea and Indian Ocean to the western and central Pacific Ocean. This is an uncommon species of coral and seems to be decreasing in abundance, and the International Union for Conservation of Nature has rated its conservation status as being "near threatened".

<i>Blastomussa wellsi</i>

Blastomussa wellsi is a species of large polyp stony coral. It is unclear in which family the genus Blastomussa belongs. This coral is found in the west and central Indo-Pacific region.

<i>Schizocyathus</i>

Schizocyathus is a monotypic genus of stony corals in the family Schizocyathidae, the only species being Schizocyathus fissilis. It is a deep water, azooxanthellate coral.

References

  1. 1 2 Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. pp. 134–135. ISBN   978-81-315-0104-7.
  2. ↑ Sprung, Julian (1999). Corals: A quick reference guide. Ricordea Publishing. pp. 220–223. ISBN   1-883693-09-8.
  3. 1 2 "Corallite". Coral Hub. Archived from the original on 2015-05-11. Retrieved 2015-04-22.
  4. ↑ "The polyp skeleton". Corals of the World. Australian Institute of Marine Science. 2013. Retrieved 2015-04-22.
  5. ↑ "Colony formation". Corals of the World. Australian Institute of Marine Science. 2013. Retrieved 2015-04-22.
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