''Galaxea'' is a genus of Colony (biology), colonial Scleractinia, stony corals in the family Euphylliidae. Common names include crystal, galaxy, starburst and tooth coral. They are abundant on Coral reef, reefs in the Indo-Pacific region and the Red Sea.Family Oculinidae: ''Galaxea''
Horizon. Retrieved 2011-12-16. They are found in water less than deep and favour turbid sites. They are sometimes kept in reef aquarium, reef aquaria.''Galaxea''
Tidal Gardens. Retrieved 2011-12-16.

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 polyp (zoology), polyps sit are small and crowded and have raised edges or may even be stalked. There are a large number of fine Septum (coral), septa on the edge of the corallites, arranged in whorls and protruding as sharp ridges. The polyps contain Symbiosis, symbiotic protists called zooxanthellae and grow in shallow water to maximise the uptake of sunlight. They often feed in the day, extending yellowish or greenish, often white tipped tentacles. They have certain specialised sweeper tentacles, long defensive organs, tipped with powerful cnidocytes which discourage other corals from living close by.

Species

The World Register of Marine Species lists the following species: *''Galaxea acrhelia'' Veron, 2000 *''Galaxea alta'' Nemenzo, 1979
*''Galaxea astreata'' (Lamarck, 1816) *''Galaxea cryptoramosa'' Fenner & Veron, 2002 *''Galaxea fascicularis'' (Linnaeus, 1767) *''Galaxea horrescens'' (Dana, 1846) *''Galaxea lauensis'' Hoffmeister, 1945 † *''Galaxea longisepta'' Fenner & Veron, 2000 *''Galaxea pauciradiata'' (Blainville, 1830) *''Galaxea paucisepta'' Claereboudt, 1990

References

{{Taxonbar, from=Q3094518 Euphylliidae Taxa named by Lorenz Oken Scleractinia genera