Coenosteum

Last updated June 06, 2019

In corals, the coenosteum is the stony skeletal material secreted by the coenosarc, the layer of living material lying between the corallites (the stony cups in which the polyps sit). 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.^[1]^[2]^[3]

Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically live in compact colonies of many identical individual polyps. Corals species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.

In corals, the coenosarc is the living tissue overlying the stony skeletal material of the coral. It secretes the coenosteum, the layer of skeletal material lying between the corallites. The coensarc is composed of mesogloea between two thin layers of epidermis and is continuous with the body wall of the polyps. The coenosarc contains the gastrovascular canal system that links the polyps and allow them to share nutrients and symbiotic zooxanthellae.

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. 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. 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.

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Mussidae is a family of stony coral in the order Scleractinia. Following a taxonomic revision in 2012, the family is now restricted to species found in the Atlantic Ocean, with Pacific species transferred to the new family Lobophylliidae. Many species are referred to as brain coral because their generally spheroid form and grooved surface resembles the convolutions of a brain. Members of this family are found in the reef aquarium trade.

The Pocilloporidae are a family of stony corals in the order Scleractinia occurring in the Pacific and Indian Oceans.

Oculinidae is a family of colonial corals.

Poritidae is a family of stony corals. Members of the family are colonial hermatypic (reef-building) corals. They are variable in size and form but most are massive, laminar or ramose as well as branching and encrusting. The corallites are compact with very little coenosteum covering the skeleton. The walls of the corallites and the septa are porous. J.E.N. Veron considers the family is not a natural grouping but is a miscellaneous collection of genera that do not fit well elsewhere.

Porites lobata, known by the common name lobe coral, is a species of stony coral in the family Poritidae. It is found growing on coral reefs in tropical parts of the Indian and Pacific Oceans.

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.

Pseudodiploria clivosa, the knobby brain coral, is a colonial species of stony coral in the family Mussidae. It occurs in shallow water in the West Atlantic Ocean and Caribbean Sea.

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.

Turbinaria is a genus of colonial stony corals in the family Dendrophylliidae. Common names for this genus include disc coral, scroll coral, cup coral, vase coral, pagoda coral and ruffled ridge coral. These corals are native to the Red Sea, Indian Ocean, Japan and the south Central Pacific Ocean.

Turbinaria reniformis, commonly known as yellow scroll coral, is a species of colonial stony coral in the family Dendrophylliidae. It is native to the Indo-Pacific region. The International Union for Conservation of Nature has rated its conservation status as being "vulnerable".

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".

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.

Simplastrea is a monotypic genus of large polyp stony coral from the Indian Ocean. It is represented by a single species, Simplastrea vesicularis.

Isophyllia is a genus of stony coral in the subfamily Mussinae of the family Mussidae.

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References

↑ 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.
↑ "Coensarc and coenosteum". Coral Hub. Retrieved 2015-04-23.
↑ "The polyp skeleton". Corals of the World. Australian Institute of Marine Science. 2013. Retrieved 2015-04-23.

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[Ruppert-1] 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] "Coensarc and coenosteum". Coral Hub. Retrieved 2015-04-23.

[3] "The polyp skeleton". Corals of the World. Australian Institute of Marine Science. 2013. Retrieved 2015-04-23.