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Galaxy Corals, Family Oculinidae

Bob Fenner

Galaxea fascicularis, Red Sea


This distinctive family (erected by Gray in 1847) is characterized by its corallites being composed of walls of solid tubes connected by smooth skeleton (coenosteum). Polyp partitions (septa) are very exsert (pronouncedly outward extending). The oculinids include zooxanthellate and azooxanthellate members.


Occur in the Indo-Pacific; Red Sea, eastern Africa out to the mid-Pacific, Mediterranean, the west African Coast and the tropical West Atlantic.

Species of Interest/Use to Aquarists:

There are a few azooxanthellate genera of oculinids as mentioned above, but these very rarely make their way into the trade. Almost exclusively encountered are the beautiful Galaxy Corals, genus Galaxea.

Genus Galaxea, Oken 1815. Galaxy, Crystal, Starry, Brittle Coral. A gorgeous species group, whose skeletons are unfortunately easily broken due to their flamboyant architecture. Dick Perrin, Tropicorium has had tremendous success at culturing forms of this genus/species whose colonies are more columnar. These captive propagated (frags) individuals are far more consistently easy to care for.

Galaxea astreata Lamarck 1816. Generally smaller corallites than G. fascicularis (3-5 versus 10 millimeter diameter), an important characteristic as these are the two common species of this genus and their extensive ranges overlap greatly. Tentacles usually only out at night. A giant colony in Bunaken, Indo. at right, below in Cebu, P.I., and another in N. Sulawesi. 

Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.
Galaxea fascicularis Linnaeus 1767). Captive colonies are ball-shaped, in the wild more like low-lying cushions that may extend meters over the bottom. Corallites well-separated with blade-like septa that may rise more than a cm. above the corallite wall. Occur in grays, greens and browns. Transparent tentacles out during the day, generally with contrasting colored tips. Below first row: open and closed (at night) in Fiji, and in the Red Sea. Second row, pix in N. Sulawesi. 
Bigger PIX:
The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Captive Care:

    A strong statement must be made re spacing these colonies from other sessile invertebrates. Their stinging sweeper tentacles are long and deliver a real wallop to animals that can't move away. Oculinids are near the topper-most of the winning by stinging scale!

Detail of a wary Clownfish, Galaxea sweepers.

Bibliography/Further Reading:

Coral Search

Borneman, Eric H. 2001. Aquarium Corals; Selection, Husbandry and Natural History. Microcosm-TFH NJ, USA. 464 pp.

Fossa, Svein A. & Alf Jacob Nilsen. 1998 (1st ed.). The Modern Coral Reef Aquarium, v.2 (Cnidarians). Bergit Schmettkamp Verlag, Borhheim, Germany. 479pp.

Hoover, John. 1998. Hawai'i's Sea Creatures. A Guide to Hawai'i's Marine Invertebrates. Mutual Publishing, Honolulu HI. 366pp. 

Humann, Paul. 1993. Reef Coral Identification; Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL.  239pp.

Veron, J.E.N. 1986. Corals of Australia and the Indo-Pacific. U. of HI press, Honolulu. 644 pp. 

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