{{Short description|Genus of corals}} {{Automatic taxobox | image = Coral (Galaxea fascicularis), mar Rojo, Egipto, 2023-04-18, DD 65.jpg | image_caption = ''Galaxea fascicularis'' | taxon = Galaxea | authority = Oken, 1815 <ref name=WoRMS>{{cite WoRMS |author=WoRMS |year=2010 |title=''Galaxea'', Oken, 1815 |id=205332 |accessdate=2011-12-16 |db=}}</ref> | subdivision_ranks = Species | subdivision = {{center|See text}} | synonyms = {{hidden begin|title = List}} * ''Acrhelia'' <small>Edwards & Haime, 1849</small> * ''Acrohelia'' <small>Milne Edwards, 1857</small> * ''Galaxea'' <small>Milne Edwards, 1857</small> {{hidden end}} }}
'''''Galaxea''''' is a genus of colonial stony corals in the family Euphylliidae. Common names include '''crystal''', '''galaxy''', '''starburst''' and '''tooth coral'''. They are abundant on reefs in the Indo-Pacific region and the Red Sea.<ref name=Horizon>[http://biophysics.sbg.ac.at/coral/oculinid.htm Family Oculinidae: ''Galaxea''] {{Webarchive|url=https://web.archive.org/web/20120501053025/http://biophysics.sbg.ac.at/coral/oculinid.htm |date=2012-05-01 }} Horizon. Retrieved 2011-12-16.</ref> They are found in water less than {{convert|20|m}} deep and favour turbid sites.<ref name=worms>{{cite WoRMS |author=WoRMS |year=2010 |title=''Galaxea fascicularis'' (Linnaeus, 1767) |id=207366 |accessdate=2011-12-16 |db=}}</ref> They are sometimes kept in reef aquaria.<ref name=TG>[http://www.tidalgardens.com/pages/coral/galaxea.html ''Galaxea''] {{Webarchive|url=https://web.archive.org/web/20120426052547/http://www.tidalgardens.com/pages/coral/galaxea.html |date=2012-04-26 }} Tidal Gardens. Retrieved 2011-12-16.</ref>
==Description== The colonies of ''Galaxea'' have various forms according to species. ''G. fascicularis'' forms long, thin columns and is one of the largest corals known. ''G. paucisepta'' and '' G. longisepta'' form flat plates, ''G. acrhelia'' is arborescent and other species form domes and rounded mounds. Their colours are mostly olives or browns but they are often tinged with purple. The corallites in which the individual polyps sit are small and crowded and have raised edges or may even be stalked. There are a large number of fine septa on the edge of the corallites, arranged in whorls and protruding as sharp ridges. The polyps contain symbiotic protists called zooxanthellae and grow in shallow water to maximise the uptake of sunlight.<ref name=Horizon/> They often feed in the day, extending yellowish or greenish, often white tipped tentacles.<ref name=worms/> They have certain specialised sweeper tentacles, long defensive organs, tipped with powerful cnidocytes which discourage other corals from living close by.<ref name=TG/>
==Species== The World Register of Marine Species lists the following species:<ref name=WoRMS/> *''Galaxea acrhelia''<small> Veron, 2000</small> *''Galaxea alta''<small> Nemenzo, 1979</small> [http://www.marinespecies.org/aphia.php?p=taxdetails&id=288114] *''Galaxea astreata''<small> (Lamarck, 1816)</small> *''Galaxea cryptoramosa''<small> Fenner & Veron, 2002</small> *''Galaxea fascicularis''<small> (Linnaeus, 1767)</small> *''Galaxea horrescens''<small> (Dana, 1846)</small> *''Galaxea lauensis''<small> Hoffmeister, 1945</small> † *''Galaxea longisepta''<small> Fenner & Veron, 2000</small> *''Galaxea pauciradiata''<small> (Blainville, 1830)</small> *''Galaxea paucisepta''<small> Claereboudt, 1990</small>
{{corals}}
==References== {{Reflist}}
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Category:Euphylliidae Category:Taxa named by Lorenz Oken Category:Scleractinia genera