''Narella'' (Gray, 1870) is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of deep-sea

soft corals Octocorallia, along with Hexacorallia, is one of the two extant classes of Anthozoa. It comprises over 3,000 species of marine and brackish animals consisting of colonial polyps with 8-fold symmetry, commonly referred informally as "soft cora ...

in the family

Primnoidae Primnoidae is a family of soft corals. Genera The World Register of Marine Species includes the following genera in the family: *'' Abyssoprimnoa'' Cairns, 2015 *'' Acanthoprimnoa'' Cairns & Bayer, 2004 *'' Aglaoprimnoa'' Bayer, 1996 *'' Aini ...

(Milne Edwards, 1857). They are

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

bottom-dwelling The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

organisms that can be found in all ocean basins, having

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

. They have a branching appearance.

History

Etymology

The name ''Narella'' is believed to be derived from the latin ''nares,'' meaning nostril, due to the resemblance of the rows of polyps to small noses.

Discovery

The present understanding of ''Narella'' and its members was only established in the late 20th century. Prior to that, many members of ''Narella'' were categorized into other genera. While the genus itself was described in 1870 by

John Edward Gray John Edward Gray (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for a z ...

, the first species in the genus was described in 1860, ''Primnoa regularis'' (now recognized as ''Narella regularis''). In 1887 several new species of ''Narella'' were discovered by Edward Wright and Théophile Studer, but were described as members of new genera ''Stachyodes'' and ''Calypterinus''. Between 1906 and 1919 many new species of ''Narella'' were discovered, though many were described as members of ''Stachyodes'' or ''Calypterinus.'' It was only in 1951 that

Frederick Bayer Frederick Merkle Bayer (October 31, 1921 — October 2, 2007) was curator emeritus at the Smithsonian Institution's National Museum of Natural History and a marine biologist who specialized in the study of soft corals. Early life and education Fre ...

synonymized these genera with ''Narella'', establishing the former as junior synonyms of the latter''.''

Distribution

''Narella'' is the most species-rich genus in ''Primnoidae.'' They are found worldwide, with species occurring in the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

, the

Hawaiian Islands The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to nort ...

, the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

, the Galápagos, and off the coast of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. While there have been a few species that are found in multiple regions, in general each region has a distinct group of

sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

species. This, along with ''Narella'''s high rate of adaptive radiation has led to researchers believing it to have many undiscovered species.

Morphology

There are over 50 recognized species of ''Narella'', but its type taxon is '' Narella regularis''. ''Narella'' are distinguished from other members of

by their conspicuous

polyps A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) en ...

which have very distinct large scales, also called

sclerites A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...

. Most species of ''Narella'' have 16 - 18 sclerites that are always arranged in pairs. Polyps in members of Primnoidae are covered at the tip by opercular scales. In ''Narella'', these eight opercular scales are paired together, giving them a symmetrical appearance. Physical differences amongst individual species of ''Narella'' primarily involve the shape and texture of the scales. These characteristics are difficult to identify in the field thus most broader identification guides focus on branching instead. The axis of corals in this genus are made of

aragonite Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation fr ...

, while their spicules are made of high Mg

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. They anchor themselves to hard substrates using calcareous discoid holdfasts.

Species

The following are species currently recognized in the genus.

References

{{Taxonbar, from=Q3955178 Primnoidae Octocorallia genera