Galaxea

Galaxea

Galaxea fascicularis
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Anthozoa
Subclass:	Hexacorallia
Order:	Scleractinia
Family:	Euphylliidae
Genus:	Galaxea Oken, 1815 ^[1]
Species
See text

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. ^[2] They are found in water less than 20 metres (66 ft) deep and favour turbid sites.^[3] They are sometimes kept in reef aquaria.^[4]

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 protozoans called zooxanthellae and grow in shallow water to maximise the uptake of sunlight.^[2] They often feed in the day, extending yellowish or greenish, often white tipped tentacles.^[3] They have certain specialised sweeper tentacles, long defensive organs, tipped with powerful cnidocytes which discourage other corals from living close by.^[4]

Species

The World Register of Marine Species lists the following species:^[1]

Galaxea acrhelia Veron, 2002
Galaxea alta Nemenzo, 1980
Galaxea astreata (Lamarck, 1816)
Galaxea cryptoramosa Fenner & Veron, 2002
Galaxea fascicularis (Linnaeus, 1767)
Galaxea longisepta Fenner & Veron, 2002
Galaxea paucisepta Claereboudt, 1990

Corals and coral reefs

Stony corals	Scleractinia Blue coral Brain coral Elkhorn coral Hermatypic coral Chalice coral Pillar coral Staghorn coral Table coral

Soft corals	Alcyonacea Black coral Bamboo coral Organ pipe coral Sea fans Sea pens

Coral reefs	Atoll reef Cay Fringing reef Microatoll Coral reef fish Census of Coral Reefs The Structure and Distribution of Coral Reefs Catlin Seaview Survey

Coral regions	List of reefs Deep-water coral African coral reefs Amazon Reef Andros, Bahamas Belize Barrier Reef Coral Sea Islands Coral Triangle Florida Keys National Marine Sanctuary Great Barrier Reef Maldives Mesoamerican Barrier Reef System New Caledonia Barrier Reef Pulley Ridge Raja Ampat Islands Red Sea Southeast Asian coral reefs

Coral diseases	Coral bleaching Black band disease Skeletal eroding band White band disease White pox disease

Protection	Coral Reef Alliance Coral reef protection Green Fins International Society for Reef Studies Project AWARE Reef Check Reef Ball

Other	Artificial reef Aquaculture of coral Coral dermatitis Precious coral Coral rag Coral reef organizations Coral sand Coralline alga Environmental issues with coral reefs Fire coral Reef resilience Rugosa (extinct) Symbiodinium Tabulata

References

1 2 WoRMS (2010). "Galaxea, Oken, 1815". World Register of Marine Species. Retrieved 2011-12-16.
1 2 Family Oculinidae: Galaxea Horizon. Retrieved 2011-12-16.
1 2 WoRMS (2010). "Galaxea fascicularis (Linnaeus, 1767)". World Register of Marine Species. Retrieved 2011-12-16.
1 2 Galaxea Tidal Gardens. Retrieved 2011-12-16.

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