hard corals text index | photo index
Phylum Cnidaria > Class Anthozoa > Subclass Zoantharia/Hexacorallia > Order Scleractinia > Family Euphylliidae
Galaxy corals
Galaxea sp.*
Family Euphylliidae
updated Nov 2019
Where seen? These small hard corals with tall, distinctive star-shaped corallites are commonly seen on many of our Southern shores. They used to be placed in Family Oculinidae. From Danwei's paper, the species found on many of our shores is Galaxea fascicularis.

Features: Colonies (10-20cm), elsewhere are said to reach 5m in diameter. Colonies are dome-shaped, forming irregular boulders and mounds. Polyps and corallites about 1cm in diameter. Corallites made up of long tubes tipped with a distinctive star-shape pattern that resembles a crown. Near the top of the long corallites, they are joined together with a common skeleton that is smooth. The skeleton is thin and quite fragile. The polyps have short thin tentacles often with white tips. When fully expanded, the tentacles hide the skeleton structure. The polyps may produce very long sweeper tentacles (up to 30cm) that clear the surrounding area of competiting corals and other encrusting animals. Colours seen include brown, blue, green and purple.

Galaxy friends: The spaces among the tubular corallites provide shelter for all kinds of animals (mussels, crabs, shrimps) often hidden deep within the colony.

Galaxy babies:
Galaxea fascicularis has a unique method of reproducing. There are two types of colonies. One type is a female colony that produces only red eggs. Another type is hermaphrodite that produces sperm and white 'eggs'. The eggs are not real eggs and help the sperm to float up to the surface where they can fertilise the real red eggs.

Human uses: These corals are among those taken for the live aquarium trade. They often do poorly in captivity. They are fragile and break easily, and collection techniques usually result in poor specimens that quickly die from disease. In addition, their habit of producing sweeper tentacles make them poor tank-mates.

Status and threats: Galaxea astreata is listed as globally Vulnerable and Galaxea fascicularis as Near Threatened by the IUCN. Like other creatures of the intertidal zone, they are affected by human activities such as reclamation and pollution. Trampling by careless visitors, and over-collection also have an impact on local populations.

Some species may form fields
of small colonies.
Pulau Hantu, Jan 10

Made of up long corallites, joined near
the top with a smooth common skeleton.
Beting Bemban Besar, Jun 09

Corallite with distinctive star- or
crown-shaped pattern at the top.
Kusu Island, May 05

Long sweeper tentacles
Pulau Semakau, Sep 05

Polyps tentacles short slender with white tips.
Sisters Island, Apr 04

Mouth in the middle of the tentacles.
Pulau Hantu, Jan 10

*Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.

Galaxy corals on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Tanah Merah, Jun 10.
Photo shared by Loh Kok Sheng on his flickr

East Coast PCN, Jul 20
Photo shared by Loh Kok Sheng on facebook.

East Coast Park (B), Jun 21
Photo shared by Loh Kok Sheng on facebook.

St. John's Island, Apr 21
Photo shared by Loh Kok Sheng on facebook.

Tanah Merah, May 09
Photo shared by Loh Kok Sheng on his blog.

Raffles Lighthouse, Jul 06

Pulau Hantu, Aug 03

Pulau Senang, Jun 10

Pulau Berkas, May 10

Tanah Merah Ferry Terminal, Jun 15

Photo shared by Loh Kok Sheng on facebook.

Galaxea species recorded for Singapore
from Danwei Huang, Karenne P. P. Tun, L. M Chou and Peter A. Todd. 30 Dec 2009. An inventory of zooxanthellate sclerectinian corals in Singapore including 33 new records **the species found on many shores in Danwei's paper.
in red are those listed as threatened on the IUCN global list.

  Family Euphylliidae
  Galaxea astreata (Vulnerable)
Galaxea fascicularis**
(Near Threatened)



  • Danwei Huang, Karenne P. P. Tun, L. M Chou and Peter A. Todd. 30 Dec 2009. An inventory of zooxanthellate sclerectinian corals in Singapore including 33 new records (pdf). Raffles Bulletin of Zoology Supplement No. 22: 69-80.
  • Veron, Jen. 2000. Corals of the World Australian Institute of Marine Science, Australia. 3 volumes.
  • Chou, L. M., 1998. A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. 128 pages.
  • Erhardt, Harry and Daniel Knop. 2005. Corals: Indo-Pacific Field Guide IKAN-Unterwasserachiv, Frankfurt. 305 pp.
  • Borneman, Eric H. 2001. Aquarium Corals: Selection, Husbandry and Natural History T.F. H Publications. 464 pp
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • Ng, P. K. L. & Y. C. Wee, 1994. The Singapore Red Data Book: Threatened Plants and Animals of Singapore. The Nature Society (Singapore), Singapore. 343 pp.
links | references | about | email Ria
Spot errors? Have a question? Want to share your sightings? email Ria I'll be glad to hear from you!
wildfactsheets website©ria tan 2008