Limestone is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of CaCO3. Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life.
Corals are colonial marine invertebrates within the subphylum 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.
An exoskeleton is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton which is enclosed underneath other soft tissues. Some large, hard and non-flexible protective exoskeletons are known as shell or armour.
Keratin 18 is a type I cytokeratin. It is, together with its filament partner keratin 8, perhaps the most commonly found products of the intermediate filament gene family. They are expressed in single layer epithelial tissues of the body. Mutations in this gene have been linked to cryptogenic cirrhosis. Two transcript variants encoding the same protein have been found for this gene.
Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolostone), which is composed of dolomite (CaMg(CO3)2). They are usually classified based on texture and grain size. Importantly, carbonate rocks can exist as metamorphic and igneous rocks, too. When recrystallized carbonate rocks are metamorphosed, marble is created. Rare igneous carbonate rocks even exist as intrusive carbonatites and, even rarer, there exists volcanic carbonate lava.
Alcyonacea are an order of sessile colonial cnidarians that are found throughout the oceans of the world, especially in the deep sea, polar waters, tropics and subtropics. Whilst not in a strict taxonomic sense, Alcyonacea are commonly known as soft corals. The term "soft coral" generally applies to organisms in the two orders Pennatulacea and Alcyonacea with their polyps embedded within a fleshy mass of coenenchymal tissue. Consequently, the term "gorgonian coral" is commonly handed to multiple species in the order Alcyonacea that produce a mineralized skeletal axis composed of calcite and the proteinaceous material gorgonin only and corresponds to only one of several families within the formally accepted taxon Gorgoniidae (Scleractinia). These can be found in order Malacalcyonacea (taxonomic synonyms of include : Alcyoniina, Holaxonia, Protoalcyonaria, Scleraxonia, and Stolonifera. They are sessile colonial cnidarians that are found throughout the oceans of the world, especially in the deep sea, polar waters, tropics and subtropics. Common names for subsets of this order are sea fans and sea whips; others are similar to the sea pens of related order Pennatulacea. Individual tiny polyps form colonies that are normally erect, flattened, branching, and reminiscent of a fan. Others may be whiplike, bushy, or even encrusting. A colony can be several feet high and across, but only a few inches thick. They may be brightly coloured, often purple, red, or yellow. Photosynthetic gorgonians can be successfully kept in captive aquaria.
Millepora dichotoma, the net fire coral, is a species of hydrozoan, consisting of a colony of polyps with a calcareous skeleton.
Bamboo coral, family Keratoisididae is a family of coral of the phylum Cnidaria. It is a commonly recognized inhabitant of the deep sea, due to the clearly articulated skeletons of the species. Deep water coral species such as this are especially affected by the practice of bottom trawling. These organisms may be an important environmental indicator in the study of long term climate change, as some specimens of bamboo coral have been discovered that are 4,000 years old. Bamboo corals were previously defined to be the family Isididae, based on their articulated skeletons with proteinaceous joints, but this family was shown to be paraphyletic after it was found in 2021 that this had evolved at least five separate times. As of 2023, the taxonomy of bamboo corals is being actively revised.
Holaxonia is a suborder of soft corals, a member of the phylum Cnidaria. Members of this suborder are sometimes known as gorgonians and include the sea blades, the sea fans, the sea rods and the sea whips. These soft corals are colonial, sessile organisms and are generally tree-like in structure. They do not have a hard skeleton composed of calcium carbonate but have a firm but pliable, central axial skeleton composed of a fibrous protein called gorgonin embedded in a tissue matrix, the coenenchyme. In some genera this is permeated with a calcareous substance in the form of fused spicules. Members of this suborder are characterized by having an unspiculated axis and often a soft, chambered central core. The polyps have eight-fold symmetry and in many species, especially in the families Gorgoniidae and Plexauridae, contain symbiotic photosynthetic algae called zooxanthellae. These soft corals are popular in salt water aquaria.
Gorgonia ventalina, the common sea fan and purple sea fan, is a species of sea fan, an octocoral in the family Gorgoniidae. It is found in the western Atlantic Ocean and the Caribbean Sea.
Primnoa(Lamororux, 1812) also known as red tree coral, is a genus of soft corals and the type genus of the family Primnoidae (Milne Edwards, 1857). They are sessile, benthic cnidarians that can be found in the North Pacific, North Atlantic, and Subantarctic South Pacific, and its members often play a vital ecological role as keystone species within their environment as a habitat and refuge for the megafauna that also inhabit those regions. This, in combination with their slow growth, makes the increasing disturbance to their habitats caused by fishing activities particularly impactful and difficult to recover from.
Primnoa pacifica or red tree coral is a species of soft coral in the family Primnoidae. It is a deep water coral found in the North Pacific Ocean, and plays an integral role in supporting benthic ecosystems. Red tree corals grow axially and radially, producing structures of calcite and gorgonian skeletons that form dense thickets. Like other species of coral, red tree coral is made of a soluble form of calcium carbonate, which forms the reef structure, as well as provides food, shelter, and nutrients for surrounding organisms. Amongst the organisms red tree corals provide a home for, many are commercially important fish and crustaceans. These areas of marine habitat are listed as Habitat Areas of Particular Concern. However, anthropogenic impacts such as bottom trawling pose large-scale threats to these habitats. There are also concerns about the effects of ocean acidification on red tree coral, since it shares many of the same properties as other corals that are suffering from bleaching.
Plexaurella nutans, the giant slit-pore sea rod, is a tall species of soft coral in the family Plexauridae. It is a relatively uncommon species and is found in shallow seas in the Caribbean region.
Hawaiian gold coral is a rare, extremely long-lived deep-sea coral found on seamounts near Hawaii. It is the only member of the monotypic genus Kulamanamana. Most colonies can live up to 2,470 years, based on a study using radiocarbon dating. In the Hawaiian Archipelago of the North Pacific Ocean, the Hawaiian gold coral is a crucial species to the ecology of Hawaiian seamounts. This is because it is a dominant macro-invertebrate found in the deep sea, and thus provides an important habitat for an array of invertebrates and fish. Gold coral tissue is reflective under light, and colonies are bioluminescent when mechanically stimulated, or touched. It is predicted that this bioluminescence perhaps attracts prey, however more research is needed to determine exactly what purpose it serves. Although it has been harvested commercially for use in jewelry for a long time, it was not formally described by taxonomists until 2012 when it was found to be related to both the genus Savalia and the octocoral-associated zoanthid, Corallizoanthus tsukaharai. Prior to being formally classified and named Kulamanamana haumeaae, the Hawaiian gold coral was previously known as Gerardia sp.
Cerevisterol (5α-ergosta-7,22-diene-3β,5,6β-triol) is a sterol. Originally described in the 1930s from the yeast Saccharomyces cerevisiae, it has since been found in several other fungi and, recently, in deep water coral. Cerevisterol has some in vitro bioactive properties, including cytotoxicity to some mammalian cell lines.
Paragorgia arborea is a species of coral in the family Paragorgiidae, commonly known as the bubblegum coral because of its bulbous branch tips. It mainly grows in depths between 200 and 1,300 metres at temperatures between 3 and 8 °C. It is found widespread in the Northern Atlantic Ocean and Northern Pacific Ocean on seamounts and knolls, and was first described by the Swedish naturalist Carl Linnaeus in 1758. P. arborea is a foundation species, providing a habitat for other species in deep sea coral ecosystems.
Paramuricea clavata, the violescent sea-whip, is a species of colonial soft coral in the family Plexauridae. It is found in shallow seas of the north-eastern Atlantic Ocean and the north-western Mediterranean Sea as well as Ionian Sea. This species was first described by the French naturalist Antoine Risso in 1826.
Leiopathes glaberrima is a species of black coral of the order Antipatharia found in the northern Atlantic Ocean and the Mediterranean Seas deep water habitats. A very slow-growing species, it is among the oldest living animals on the planet.
Marine biogenic calcification is the production of calcium carbonate by organisms in the global ocean.
The Arctic Ocean covers an area of 14,056,000 square kilometers, and supports a diverse and important socioeconomic food web of organisms, despite its average water temperature being 32 degrees Fahrenheit. Over the last three decades, the Arctic Ocean has experienced drastic changes due to climate change. One of the changes is in the acidity levels of the ocean, which have been consistently increasing at twice the rate of the Pacific and Atlantic oceans. Arctic Ocean acidification is a result of feedback from climate system mechanisms, and is having negative impacts on Arctic Ocean ecosystems and the organisms that live within them.
