''Gorgonia ventalina'', the common sea fan and purple sea fan, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of sea fan, an

octocoral Octocorallia (also known as Alcyonaria) is a class of Anthozoa comprising around 3,000 species of water-based organisms formed of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians (sea fan ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Gorgoniidae Gorgoniidae is a family of soft corals, a member of the subclass Octocorallia in the phylum Cnidaria. Nearly all the genera and species are native to the east and west coasts of America. Characteristics Originally the members of the family G ...

. It is found in the western Atlantic Ocean and the Caribbean Sea.

Description

''G. ventalina'' is a fan-shaped

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 ...

coral with several main branches and a latticework of linking smaller branches. The skeleton 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 gorgonion, 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 compound. The calyces in which the polyps are embedded are in two rows along the branches. Many of the smaller branches are compressed in the plane of the fan, which distinguishes this species from the Venus sea fan (''

Gorgonia flabellum ''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, a sessile colonial soft coral. Description The Venus sea fan is a delicate-looking colonial soft ...

''). It often has small accessory fans growing out sideways from the main fan. It grows to 1.5 m (5 ft) tall and is variable in colour, being whitish, yellow, or pale purple. The main branches are often purple and the fan is orientated at right angles to the current.

Distribution and habitat

The purple sea fan is found in the western Atlantic and Caribbean, with a range extending from

Bermuda ) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , e ...

and

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

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

Curaçao Curaçao ( ; ; pap, Kòrsou, ), officially the Country of Curaçao ( nl, Land Curaçao; pap, Pais Kòrsou), is a Lesser Antilles island country in the southern Caribbean Sea and the Dutch Caribbean region, about north of the Venezuela coast ...

. It grows near the shore in shallow water in areas with strong wave action and on deeper outer reefs with strong currents down to a depth of about .

Ecology

''G. ventalina'' 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 ...

. Each polyp extends its eight tentacles to catch plankton drifting past on the current. Its 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 ...

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 unicell ...

''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. The skeleton of ''G. ventalina'' contains hard structures known as

sclerite 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 ...

s which are unpalatable to

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

. It also contains certain

secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norm ...

s in its tissues which are distasteful. The

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to matc ...

Tritonia hamnerorum ''Tritonicula hamnerorum'' is a species of dendronotid nudibranch. It is a marine gastropod mollusc in the family Tritoniidae. A number of Caribbean species of ''Tritonia'' were moved to a new genus ''Tritonicula'' in 2020 as a result of an ...

'' seems undeterred by these defences and is often found associated with the coral. While feeding on the coral, it concentrates the metabolites in its tissues which render it unpleasant to potential predators. This is because ''T.hamnerorum'' sequesters the chemical compound julieannfuran from G.ventalina to use as a chemical deterrent to predators. This coral is sometimes attacked by the fungus ''

Aspergillus sydowii ''Aspergillus sydowii'' is a pathogenic fungus that causes several diseases in humans. It has been implicated in the death of sea fan corals (''Gorgonia'' spp.) in the Caribbean Sea. Taxonomy The species was first described in 1913 as ''Sterigm ...

'' which causes

aspergillosis Aspergillosis is a fungal infection of usually the lungs, caused by the genus ''Aspergillus'', a common mould that is breathed in frequently from the air around, but does not usually affect most people. It generally occurs in people with lung di ...

. This results in damaged patches,

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

s, purpling of the tissues, and even coral death. Several

epizootic In epizoology, an epizootic (from Greek: ''epi-'' upon + ''zoon'' animal) is a disease event in a nonhuman animal population analogous to an epidemic in humans. An epizootic may be restricted to a specific locale (an "outbreak"), general (an "epi ...

s have occurred in the Caribbean on corals growing in stressful conditions such as in low-

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

water in estuaries which seem especially susceptible. A parasite of the class

Labyrinthulomycetes The Labyrinthulomycetes (ICBN) or Labyrinthulea (ICZN) are a class of protists that produce a network of filaments or tubes, which serve as tracks for the cells to glide along and absorb nutrients for them. The two main groups are the labyrint ...

in the family ''Thraustochytriidae'' has been found to have similar effects of damaged purple patches on the fan called multifocal purple spots. A study done in the U.S. Virgin Islands has shown that ''G. ventalina'' has a high

ecological resilience In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or disturbance by resisting damage and recovering quickly. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms ...

with populations maintaining their densities after two hurricanes in 2017. Edmunds, Peter J. “High Ecological Resilience of the Sea Fan Gorgonia Ventalina during Two Severe Hurricanes.” PeerJ, vol. 8, 11 Nov. 2020, doi:10.7717/peerj.10315.

References

{{Taxonbar, from=Q3329148 Gorgoniidae Corals described in 1758 Taxa named by Carl Linnaeus