''Gorgonia flabellum'', also known as the Venus fan, Venus sea fan, West Indian sea fan, and purple gorgonian seafan, is a species of

sea fan Alcyonacea, or soft corals, are an order of corals. In addition to the fleshy soft corals, the order Alcyonacea now contains all species previously known as "gorgonian corals", that produce a more or less hard skeleton, though quite different f ...

, a

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 ...

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...

soft coral Alcyonacea, or soft corals, are an order of corals. In addition to the fleshy soft corals, the order Alcyonacea now contains all species previously known as "gorgonian corals", that produce a more or less hard skeleton, though quite different f ...

Description

The Venus sea fan is a delicate-looking

soft coral in the form of a fan composed of a lattice of branches in a single plane. The coral grows from a small base, forming several main branches with side branches and a network of small branchlets. The Venus sea fan is similar in appearance to ''

Gorgonia ventalina ''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. Description ''G. ventalina'' is a fan-shaped col ...

'', but has a slightly more untidy shape and short, stubby side growths coming out of the main plane. In ''G. flabellum'', the branches are flattened at right angles to the plane of the fan, while in ''G. ventalina'', the branches are either round or flattened parallel to the plane of the fan. The wide-mesh sea fan (''

Gorgonia mariae ''Gorgonia mariae'', commonly known as the wide-mesh sea fan, is a species of sea fan, a sessile colonial soft coral in the family Gorgoniidae. It occurs in the tropical western Atlantic Ocean and the Caribbean Sea at depths down to about . Desc ...

'') is also similar in appearance, but at only 30 cm, is smaller, and many of the branchlets do not interconnect. The Venus sea fan is white, yellowish, or pale lavender. The fan is often found oriented perpendicular to the incoming waves and can grow to a height of .

Distribution and habitat

The Venus sea fan is very common in the

Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...

, and in this location is easily distinguishable from ''G. ventalina''. In other parts of its range,

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

and the

Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc betwe ...

, however, the two species are more easily confused. It is a shallow-water species seldom exceeding a depth of and favours locations with strong wave action.

Biology

The skeleton of the Venus sea fan is composed of

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 ...

and a

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

-like substance. Embedded in this are the coral polyps, each of which is a

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

and extends its eight tentacles to catch

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

drifting past with the current. The tissues contain

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

algae ''

Symbiodinium : ''This is about the genus sometimes called Zoox. For the company, see Zoox (company)'' ''Symbiodinium'' is a genus of dinoflagellates that encompasses the largest and most prevalent group of endosymbiotic dinoflagellates known. These unicellul ...

'' spp. which are

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

and use sunlight to create organic carbon compounds which are then available to the host coral.

References

{{Taxonbar, from=Q2310542 Gorgoniidae Corals described in 1758 Taxa named by Carl Linnaeus