Orbicella

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Orbicella
Orbicella faveolata, Flower Garden Banks.jpg
Orbicella faveolata
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Cnidaria
Class: Hexacorallia
Order: Scleractinia
Family: Merulinidae
Genus: Orbicella
Dana, 1846 [1]
Species
See text

Orbicella is a genus of stony corals in the Merulinidae family. The Orbicella species complex comprises three sister species, namely Orbicella faveolata , Orbicella annularis and Orbicella franksi , all of which are shallow-water, zooxanthellate species and are native to the tropical western Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.

Contents

These corals are ubiquitous and major reef-builders in the Caribbean. Their similar colony morphologies misled scientists to historically lump them into a single species, Montastraea annularis, which included three morphotypes “bumpy”, “columnar” and “massive”. These growth forms were believed to arise as a response to abiotic factors (e.g., depth, light availability). This taxonomic classification was challenged by further ecological, reproductive, genetic, and morphologic evidence, which led to the re-description of three separate species, Montastraea faveolata (massive), M. annularis (columnar) and M. franksi (bumpy). [2] [3] [4]

A taxonomic revision published in 2012 established that the “Montastraea annularis species complex” formed a separate clade now in the genus Orbicella with three species names (O. faveolata, O. annularis, O. franksi). [5] O. annularis and O. faveolata are commonly called the boulder star coral [6] and the mountainous star coral, [7] respectively.

Characteristics

The colonies of these corals are massive and form dome-shaped mounds, with uneven surfaces and bulging projections. The corallites are small and closely packed. These corals are mostly some shade of light brown but sometimes have green oral discs. [8]

Skeleton properties

Orbicella skeleton is made from CaCO3 in the crystal form of aragonite. The growth rate has been correlated with depth. [9] In addition, the skeleton also contains brucite [Mg(OH)2] in the interseptal spaces (microbialites). These brucite particles encrusts microbes growing inside the coral skeleton. [10]

Speciation and reproductive barriers

Speciation is the gradual process by which species originate. Speciation can be studied from many perspectives, but regardless of the point of view it often requires reproductive isolation between species. In the case of the Orbicella, these species are broadcast spawner corals and release gametes annually in the same evening into the water column. The night of spawning is normally in August and September, the warmest months of the year, and five to eight nights after the full moon. Some authors argue these species, specifically O. annularis and O. faveolata, spawn simultaneously, [11] but most reports support that the Orbicella species are temporally isolated by a few hours. [12] [13] It is thought that the specific timing of these spawning events is dictated by light availability and perceived sunset/moonrise times. Sperm and eggs are released packed in small bundles that break open when they reach the water surface due to the surface tension. Timing is important to improve the chances of gametes finding each other in the water column. Hybridization studies reported some success in crossing O. annularis and O. franksi. Yet crosses with O. faveolata are consistently unsuccessful. However, these crosses were done in laboratory conditions that are not natural (covering O. annularis in advance to trick it into spawning earlier) so these crosses are unlikely to occur in nature. Furthermore, in nature gametes get diluted and age quickly. [12] Hence, Orbicella species are reproductively isolated by at least these two ways, allowing for species distinction and evolution.

Species

The following species are currently recognized by the World Register of Marine Species  : [1]

Related Research Articles

<span class="mw-page-title-main">Coral</span> Marine invertebrates of the class Anthozoa

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

<span class="mw-page-title-main">Scleractinia</span> Order of Hexacorallia which produce a massive stony skeleton

Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mouth is fringed with tentacles. Although some species are solitary, most are colonial. The founding polyp settles and starts to secrete calcium carbonate to protect its soft body. Solitary corals can be as much as 25 cm (10 in) across but in colonial species the polyps are usually only a few millimetres in diameter. These polyps reproduce asexually by budding, but remain attached to each other, forming a multi-polyp colony of clones with a common skeleton, which may be up to several metres in diameter or height according to species.

<i>Montastraea</i> Genus of corals

Montastraea is a genus of colonial stony coral found in the Caribbean seas. It is the only genus in the monotypic family Montastraeidae and contains a single species, Montastraea cavernosa, known as great star coral. It forms into massive boulders and sometimes develops into plates. Its polyps are the size of a human thumb and fully extend at night.

<span class="mw-page-title-main">Pillar coral</span> Species of coral

Pillar coral is a hard coral found in the western Atlantic Ocean and the Caribbean Sea. It is the only species in the monotypic genus Dendrogyra. It is a digitate coral -that is, it resembles fingers or a cluster of cigars, growing up from the sea floor without any secondary branching. It is large and can grow on both flat and sloping surfaces at depths down to 20 m (65 ft). It is one of the few types of hard coral in which the polyps can commonly be seen feeding during the day.

<span class="mw-page-title-main">Mussidae</span> Family of corals

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.

<i>Orbicella annularis</i> Species of coral

Orbicella annularis, commonly known as the boulder star coral, is a species of coral that lives in the western Atlantic Ocean and is the most thoroughly studied and most abundant species of reef-building coral in the Caribbean to date. It also has a comprehensive fossil record within the Caribbean. This species complex has long been considered a generalist that exists at depths between 0 and 80 meters that grew into varying colony shapes in response to differing light conditions. Only recently with the help of molecular techniques has O. annularis been shown to be a complex of at least three separate species. Those species are divided into O. annularis, O. faveolata, and O. franksi. This coral was originally described as Montastraea annularis.

<span class="mw-page-title-main">Zoanthus sociatus</span> Species of coral

Zoanthus sociatus, commonly known as the green sea mat or button polyp, is a zoanthid usually found in shallow reef zones of tropical regions from Caribbean to southeastern Brazil. Z. sociatus is currently being studied for its use against human lymphatic parasites.

<span class="mw-page-title-main">Yellow-band disease</span> Bacterial disease of coral

Yellow-band disease is a coral disease that attacks colonies of coral at a time when coral is already under stress from pollution, overfishing, and climate change. It is characterized by large blotches or patches of bleached, yellowed tissue on Caribbean scleractinian corals.

<i>Siderastrea siderea</i> Species of coral

Siderastrea siderea, commonly known as massive starlet coral or round starlet coral, is a stony coral in the family Siderastreidae. It is found in shallow parts of the western Atlantic Ocean as solid boulder-shaped or domed structures.

<i>Diploria</i> Genus of corals

Diploria is a monotypic genus of massive reef building stony corals in the family Mussidae. It is represented by a single species, Diploria labyrinthiformis, commonly known as grooved brain coral and is found in the western Atlantic Ocean and Caribbean Sea. It has a familiar, maze-like appearance.

<i>Colpophyllia</i> Genus of corals

Colpophyllia is a genus of stony corals in the family Mussidae. It is monotypic with a single species, Colpophyllia natans, commonly known as boulder brain coral or large-grooved brain coral. It inhabits the slopes and tops of reefs, to a maximum depth of fifty metres. It is characterised by large, domed colonies, which may be up to two metres across, and by the meandering network of ridges and valleys on its surface. The ridges are usually brown with a single groove, and the valleys may be tan, green, or white and are uniform in width, typically 2 centimetres. The polyps only extend their tentacles at night.

<i>Pseudodiploria clivosa</i> Species of coral

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.

<i>Pocillopora verrucosa</i> Species of coral

Pocillopora verrucosa, commonly known as cauliflower coral, rasp coral, or knob-horned coral, is a species of stony coral in the family Pocilloporidae. It is native to tropical and subtropical parts of the Indian and Pacific Oceans.

<i>Dipsastraea speciosa</i> Species of coral

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.

<i>Orbicella faveolata</i> Species of coral

Orbicella faveolata, commonly known as mountainous star coral, is a colonial stony coral in the family Merulinidae. Orbicella faveolata is native to the coral coast of the Caribbean Sea and the Gulf of Mexico and is listed as "endangered" by the International Union for Conservation of Nature. O. faveolata was formerly known as Montastraea faveolata.

<i>Orbicella franksi</i> Species of coral

Orbicella franksi, commonly known as boulder star coral, is a colonial stony coral in the family Merulinidae. It is native to shallow waters in the Caribbean Sea, the Gulf of Mexico, the Bahamas, Bermuda and Florida, and is listed as a "vulnerable species" by the International Union for Conservation of Nature.

<i>Isophyllia</i> Genus of corals

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

<i>Pseudodiploria</i> Genus of corals

Pseudodiploria is a genus of stony corals in the subfamily Faviinae of the family Mussidae. This genus was erected in 2012, having been split off from the genus Diploria. This genus is found in the tropical and subtropical West Atlantic Ocean and the Caribbean Sea.

<i>Leptastrea</i> Genus of corals

Leptastrea is a genus of massive reef building stony corals known primarily from the Indo-Pacific. Although previously assigned to Faviidae, Budd et al. (2012) assigned it to Scleractinia incertae sedis based on phylogenetic results demonstrating the polyphyly of Faviidae. Assigned to family Leptastreidae by Rowlett (2020).

References

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