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Galaxea (Oculinidae)

Welcome to the Galaxea genus landing page. In this section, you will find general information about this genus and tips on how to identify it. If you are looking to confirm an observation made with the Coral Finder, use the image browser below to verify what you saw underwater.  The nature of this genus is highly distinctive, which means that it is unlikely to confuse it with other members of the group.

The suggested reading list at the end of the page clearly shows how extensively Galaxea has been studied, with research throwing light onto a wide range of topics from calcification of the coral skeleton (Al-Horani et al., 2003), to intraspecific competition (Hidaka, 1984) and species associations (Humes, 1996).  We recommend you have a look through the information if you have a specific interest or question, or for more general identification issues check out Corals of the World (Veron, 2000).

Vital Statistics

  • 7 species
  • Coral Finder p. 5, 16
  • COTW – Vol 2 p. 106-117


Widespread in the Indo-Pacific.

ID Tips

Galaxea forms a wide range of growth forms from branching through to columnar, massive or thickly encrusting.  It is common in an array of reef environments.

The tubular corallites are highly distinctive due to the exsert or blade-like septa which form a sharp crown around each centre.  Be aware that when the tentacles are extended, they may mask the septa.  Wafting your hand over the colony surface will cause the tentacles to retract, exposing the exsert septa.

(slide show with photos of exsert septa with and without tentacles extended.)

Similar Genera

The Coral Finder lists Galaxea in two key groups (branching and massive corals, CF p5 & p16), but the highly distinctive nature of septa means that this genus is easily differentiated from other members of the two groups.


Taxonomic Changes

Learning Resources

Coral Hub

  • Oculinidae family page


Suggested Reading – Identification Tools

  • Anonymous. (2004). Porites Link, 1807, Galaxea Oken, 1815, Mussa Oken, 1815 and Dendrophyllia Blainville, 1830 (Anthozoa, Scleractinia): generic names conserved. Bulletin of Zoological Nomenclature, 61(Part 1), 51-53.
  • Claereboudt, M. (1990). Galaxea paucisepta nom. nov. (for G. pauciradiata), rediscovery and redescription of a poorly known scleractinian species (Oculinidae). Galaxia, 9, 1-18.
  • Hidaka, M., & Yamazato, K. (1985). Color morphs of Galaxea fascicularis found in the reef around the Sesoko Marine Science Center Japan. Galaxea, 4(1), 33-36.
  • Veron, J. E. N. (1985). Corals of Australia and the Indo-Pacific. Sydney: Angus and Robertson.
  • Veron, J. E. N. (2000). Corals of the World. Melbourne: Australian Institute of Marine Science.
  • Veron, J. E. N. (2002). New species described in ‘Corals of the World’: Australian Institute of Marine Science.
  • Veron, J. E. N., & Pichon, M. (1980). Scleractinia of Eastern Australia.  Part 3, Families Agaraciidae, Siderastreidae, Fungiidae, Oculinidae, Merulinidae, Mussidae, Pectiniidae, Carophylliidae, Dendrophylliidae. Australian Institute of Marine Science Monograph Series, IV, 471.

Suggested Reading – Other Topics

  • Abe, M., Hayato, H., Watanabe, T., & Hidaka, M. (2005). Preliminary studies on the distribution of morphotypes of the coral Galaxea fascicularis in reefs around Okinawa and Ishigaki Islands. Zoological Science, 22(12), 1436-1436.
  • Abe, M., Suzuki, Y., Hayakawa, H., Watanabe, T., & Hidaka, M. (2006). Diversity of the coral Galaxea fascicularis in reefs around Okinawa. Zoological Science, 23(12), 1152-1152.
  • Abe, M., Watanabe, T., Suzuki, Y., & Hidaka, M. (2008). Genetic and morphological differentiation in the hermatypic coral Galaxea fascicularis in Okinawa, Japan. Plankton & Benthos Research, 3(3), 174-179.
  • Al-Horani, F. A., Al-Moghrabi, S. M., & de Beer, D. (2003). The mechanism of calcification and its relation to photosynthesis and respiration in the scleractinian coral Galaxea fascicularis. Marine Biology, 142(3), 419-426.
  • Al-Horani, F. A., Ferdelman, T., Al-Moghrabi, S. M., & de Beer, D. (2005). Spatial distribution of calcification and photosynthesis in the scleractinian coral Galaxea fascicularis. Coral Reefs, 24(1), 173-180.
  • Bhagooli, R., & Hidaka, M. (2004). Release of zooxanthellae with intact photosynthetic activity by the coral Galaxea fascicularis in response to high temperature stress. Marine Biology, 145(2), 329-337.
  • Clode, P. L., & Marshall, A. T. (2003). Variation in skeletal microstructure of the coral Galaxea fascicularis: Effects of an aquarium environment and preparatory techniques. Biological Bulletin, 204(2), 138-145.
  • Crabbe, M. J. C., & Smith, D. J. (2006). Modelling variations in corallite morphology of Galaxea fascicularis coral colonies with depth and light on coastal fringing reefs in the Wakatobi Marine National Park (SE Sulawesi, Indonesia). Computational Biology and Chemistry, 30(2), 155-159.
  • Ebisawa, T., Yamamura, A., Kameda, Y., Hayakawa, K., Nagata, K., & Tanokura, M. (2009). Crystallization and preliminary X-ray analysis of a monomeric mutant of Azami-Green (mAG), an Aequorea victoria green fluorescent protein-like green-emitting fluorescent protein from the stony coral Galaxea fascicularis. Acta Crystallographica Section F-Structural Biology and Crystallization Communications, 65, 1292-1295.
  • Hidaka, M., & Yamazato, K. (1984). Intraspecific interactions in a scleractinian coral, Galaxea fascicularis – induced formation of sweeper tentacles. Coral Reefs, 3(2), 77-85.
  • Higuchi, T., Fujimura, H., Arakaki, T., & Oomori, T. (2009). The synergistic effects of hydrogen peroxide and elevated seawater temperature on the metabolic activity of the coral Galaxea fascicularis. Marine Biology, 156(4), 589-596.
  • Humes, A. G. (1996). Copepoda associated with the scleractinian coral Galaxea in the Indo-Pacific. Publications of the Seto Marine Biological Laboratory, 37(1-2), 1-49.
  • Kusen, J. D., & Yamazato, K. (1986). Intra-specific variation of Galaxea fascicularis Linnaeus. Zoological Science, 3(6), 1105-1105.
  • Marshall, A. T., & Clode, P. L. (2002). Effect of increased calcium concentration in sea water on calcification and photosynthesis in the scleractinian coral Galaxea fascicularis. Journal of Experimental Biology, 205(14), 2107-2113.
  • Miyazaki, I., Hidaka, M., & Yamazato, K. (1984). Mechanism of changes in the nematocyst composition during formation of sweeper tentacles in the coral Galaxea fascicularis. Zoological Science, 1(6), 982-982.
  • Titlyanov, E. A., Titlyanova, T. V., & Yamazato, K. (2001). Formation, growth and photo-acclimation of colonies of the hermatypic coral Galaxea fascicularis under different light conditions. Symbiosis, 30(4), 257-274.
  • Yamada, G., Fujimori, K., Yamada, M. O., Minami, T., Tohno, S., & Tohno, Y. (1998). Trace elements found to be variable in two coral reef species, Heliofungia actiniformis and Galaxea fascicularis, collected from the Ryukyu Islands. Biological Trace Element Research, 65(2), 167-180.
  • Yamazato, K., Yoshida, S., & Yamashiro, H. (1987). A note on the colonial growth in a coral Galaxea fascicularis. Galaxea, 6(1), 119-124.