Alcyonacea

Source: Wikipedia, the free encyclopedia.

Soft coral
Cladiella sp.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Cnidaria
Class: Octocorallia
Order: Alcyonacea
Lamouroux, 1812 [1]
Suborders

See text

Synonyms
  • Gorgonacea

Alcyonacea are an order of sessile colonial

fan. Others may be whiplike, bushy, or even encrusting.[4] 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
.

About 500 different species of gorgonians are found in the oceans of the world, but they are particularly abundant in the shallow waters of the Western Atlantic, including Florida, Bermuda, and the West Indies.[5]

Anatomy

Vieques Island, Puerto Rico
Gorgonian with reproductive stage, Caribbean Sea at Cabrits National Park, Dominica
A close-up of an alcyonacean showing individual polyps

The structure of a gorgonian colony varies. In the suborder Holaxonia, skeletons are formed from a flexible, horny substance called gorgonin. The suborder Scleraxonia species are supported by a skeleton of tightly grouped calcareous spicules. Also, some species encrust like coral.[6]

Measurements of the gorgonin and calcite within several long-lived species of gorgonians can be useful in paleoclimatology and paleoceanography, as their skeletal growth rate and composition are highly correlated with seasonal and climatic variation.[7][8][9]

Features

Soft corals contain minute, spiny skeletal elements called sclerites, useful in species identification. Sclerites give these corals some degree of support and give their flesh a spiky, grainy texture that deters predators. In the past, soft corals were thought to be unable to lay new foundations for future corals, but recent findings suggest that colonies of the leather-coral genus Sinularia are able to cement sclerites and consolidate them at their base into alcyonarian spiculite,[10] thus making them reef builders.

Unlike

zooxanthella
as a major energy source. However, most readily eat any free-floating food, such as zooplankton, out of the water column. They are integral members of the reef ecosystem and provide habitat for fish, snails, algae, and a diversity of other marine species.

Despite being dominated by "soft corals", the order Alcyonacea now contains all species known as "gorgonian corals", that produce a hard skeleton made from gorgonin, a protein unique to the group that makes their skeletons quite different from "true" corals (Scleractinia). These "gorgonion corals" can be found in suborders Holaxonia, Scleraxonia, and Stolonifera.

Many soft corals are easily collected in the wild for the reef aquarium hobby, as small cuttings are less prone to infection or damage during shipping than stony corals. Nevertheless, home-grown specimens tend to be more adaptable to aquarium life and help conserve wild reefs. Soft corals grow quickly in captivity and are easily divided into new individuals, and so those grown by aquaculture are often hardier and less expensive than imported corals from the wild.

Ecology

Purple sea whip gorgonian
Fossil gorgonian holdfast on a Miocene limestone surface, Czech Republic

Each gorgonian polyp has eight

filter feeding
, is facilitated when the "fan" is oriented across the prevailing current to maximise water flow to the gorgonian, hence food supply.

Some gorgonians contain algae, or

symbiotic relationship assists in giving the gorgonian nutrition by photosynthesis
. Gorgonians possessing zooxanthellae are usually characterized by brownish polyps.

Gorgonians are found primarily in shallow waters, though some have been found at depths of several thousand feet.[4][6] The size, shape, and appearance of gorgonians can be correlated with their location. The more fan-shaped and flexible gorgonians tend to populate shallower areas with strong currents, while the taller, thinner, and stiffer gorgonians can be found in deeper, calmer waters.[4]

Other fauna, such as

Hippocampus denise
, are obligate residents on gorgonians. H. bargibanti is limited to two species in the single genus Muricella.

Gorgonians produce unusual

Xenia species.[17]

Suborders and families

The World Register of Marine Species lists these suborders and families:[18]

References

  1. ^ van Ofwegen, L. (2011). "Alcyonacea Lamouroux, 1812". WoRMS. World Register of Marine Species. Retrieved 15 December 2011.
  2. ^ Bayer, F. M. (1961). The shallow-water Octocorallia of the West Indian region. Studies on the Fauna of Curaçao and other Caribbean Islands, 12(1), 1-373.; Córdova-Isaza, A., Jiménez-Mármol, S., Guerra, Y., & Salas-Sarduy, E. (2023). Enzyme Inhibitors from Gorgonians and Soft Corals. Marine Drugs, 21(2), 104. https://doi.org/10.3390/md21020104; Raimundo, I., Silva, S., Costa, R., & Keller-Costa, T. (2018). Bioactive Secondary Metabolites from Octocoral-Associated Microbes—New Chances for Blue Growth. Marine Drugs, 16(12), 485. https://doi.org/10.3390/md16120485
  3. ^ Daly, M., M.R. Brugler, P. Cartwright, A.G. Collins, M.N. Dawson, D.G. Fautin, S.C. France, C.S. McFadden, D.M. Opresko, E. Rodriquez, S.L. Romano, J.L. Stake. (2007). The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus. Zootaxa. (1668): 127–182., available online at http://www.mapress.com/zootaxa/2007f/zt01668p182.pdf; McFadden, C.S.; van Ofwegen, L.P.; Quattrini, A.M. (2022) Revisionary systematics of Octocorallia (Cnidaria: Anthozoa) guided by phylogenomics. Bulletin of the Society of Systematic Biologists. 1(3), 8735, pp. 1-79. Available online at https://ssbbulletin.org/index.php/bssb/article/view/8735 page(s): 21; Schoch CL, et al. NCBI Taxonomy: a comprehensive update on curation, resources and tools. Database (Oxford). 2020: baaa062. PubMed: 32761142 PMC: PMC7408187.
  4. ^
    ISBN 1-890087-47-5
    .
  5. ^ "Sea Fan". University of Delaware Graduate College of Marine Studies. Archived from the original on 17 April 2006. Retrieved 23 September 2007.
  6. ^
    ISBN 0-8120-9598-7
    .
  7. S2CID 7432164
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  8. ISBN 978-3-540-24136-2
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  9. S2CID 128703481
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  10. doi:10.1007/s00338-011-0765-z
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  11. ISBN 3-89356-033-5
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  12. ^ Agbayani, Eli (5 June 2007). "Hippocampus bargibanti, Pygmy seahorse". FishBase. Retrieved 22 September 2007.
  13. PMID 19387501
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  14. doi:10.3354/meps240117
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  15. ^ Attenborough, David (12 November 2017). ""Coral Reefs"". Blue Planet II. Episode 3. BBC One.
  16. doi:10.1016/0022-0981(87)90130-4
    .
  17. ^ García-Matucheski, S. and Muniain, C. (2011). Predation by the nudibranch Tritonia odhneri (Opisthobranchia:Tritoniidae) on octocorals from the South Atlantic Ocean. Marine Biodiversity, 41(2), 287–297.
  18. ^ "WoRMS - World Register of Marine Species - Alcyonacea". marinespecies.org. Retrieved 22 March 2018.

External links

Wikimedia Commons has media related to Alcyonacea.
Wikispecies has information related to Gorgonacea.
Wikispecies has information related to Alcyonacea.
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