Brain coral (Platygyra sinensis)

Synonyms: Coeloria sinensis
KingdomAnimalia
PhylumCnidaria
ClassAnthozoa
OrderScleractinia
FamilyFaviidae
GenusPlatygyra (1)
SizeColony diameter: c. 1 m (1)
Top facts

Platygyra sinensis is classified as Least Concern (LC) on the IUCN Red List (1) and is listed on Appendix II of CITES (2).

Platygyra sinensis is a widespread coral that typically forms large, domed colonies (3) (4) (5) up to a metre or more in diameter (1). The diameter of its colonies often decreases with increasing water depth (4), and the colonies may sometimes also be flat (3) (4) (5).

Platygyra sinensis is often known as a ‘brain coral’ due to the meandering, brain-like pattern of ridges, or walls, across its surface. In this species, the walls are relatively thin (3) (5) and are usually separated by short ‘valleys’, although longer, meandering valleys do also sometimes occur (4). The colonies of Platygyra sinensis display a wide range of colours, with some being dull and others quite bright (3) (4) (5).

As in all corals, the colonies of Platygyra sinensis consist of numerous, anemone-like animals known as polyps, which have a sac-like body and a central ‘mouth’, surrounded by tentacles. The polyps secrete a hard skeleton, with the skeleton of an individual polyp being known as a ‘corallite’ (3) (6). In Platygyra sinensis, each corallite has internal projections, known as septa, which in this species are thin, evenly spaced, and have tooth-like indentations along their edges (3) (4) (5).

The corallites of Platygyra sinensis share common walls (3) (4) (5), and the mouths of the polyps are aligned along the colony’s valleys, with most valleys only having one mouth, but more elongated valleys sometimes having several (4) (5).

Platygyra sinensis is widespread in the Indian Ocean, including the Red Sea and Arabian Gulf, as well as in the western and central Pacific Ocean (1) (3) (4) (5).

Usually found at depths of up to 30 metres (1), Platygyra sinensis occurs in most types of reef habitat (1) (3) (4). However, it particularly favours the margins of back reefs, which are the more sheltered, shallower parts of the reef closest to the shore (1) (3).

Like all species in the Faviidae family, Platygyra sinensis is a zooxanthellate coral, meaning that it obtains most of its nutrients from symbiotic algae, known as zooxanthellae, which live within its tissues. The zooxanthellae provide the coral with nutrients through photosynthesis, but this restricts corals such as Platygyra sinensis to living in relatively clear, warm, shallow waters where photosynthesis can take place. In return for nutrients, the coral provides the zooxanthellae with a safe, stable environment in which to live (3) (6).

In addition to receiving nutrients in this way, Platygyra sinensis is able to supplement its diet with tiny zooplankton, which it catches using stinging cells on its tentacles. The tentacles of this species are usually only extended for feeding at night, and are retracted during the day (3).

Like other corals, Platygyra sinensis is able to reproduce asexually by a process known as ‘budding’, in which a polyp divides into two or more new polyps. Corals also reproduce sexually, usually by releasing large numbers of eggs and sperm into the water column, where the eggs are fertilised and develop into larvae. The larvae eventually settle onto the substrate and develop into polyps, starting new colonies (3).

Relatively little information is available on reproduction in Platygyra sinensis, but it is reported to have pink eggs and is hermaphroditic, with each polyp producing both eggs and sperm. In the Great Barrier Reef, off the coast of Australia, Platygyra sinensis has been recorded taking part in mass spawning events with other coral species, with most colonies releasing their eggs and sperm over a number of consecutive nights. Spawning in this region has been recorded in spring, between October and November, and usually occurs after a full moon. Platygyra sinensis has been found to spawn around three to four hours after sunset (7).

Although it is widespread and relatively common, and not currently considered at risk of extinction, Platygyra sinensis is assumed to be declining based on the loss and degradation of its reef habitats (1). Overall, around 20 percent of the world’s coral reefs have already been destroyed (8).

Like other corals, Platygyra sinensis faces a range of threats, the most serious of which is likely to be global climate change. Rising sea temperatures can cause corals to expel their zooxanthellae, weakening the coral and often resulting in death. This process, known as ‘bleaching’, can also make corals more vulnerable to disease. In addition, climate change may cause more frequent, violent storms, which can damage corals, while rising carbon dioxide levels are increasing ocean acidity and affecting the ability of corals to form their hard skeletons (1) (6) (8) (9).

Platygyra sinensis is also likely to be affected by more localised threats to reefs, including pollution, sedimentation, destructive fishing practices, invasive species, and human recreation and tourism (1) (6) (8) (9). Platygyra sinensis is also collected for the aquarium trade. Fortunately, its widespread distribution and large population help make this species more resilient to these threats (1).

Platygyra sinensis is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that international trade in this species should be carefully controlled (2). Although parts of its range fall within Marine Protected Areas (1), enforcement in these areas is often poor (6).

Recommended measures for the conservation of Platygyra sinensis and other corals include further research into its populations, ecology and resistance to various threats, as well as disease control and the expansion of protected areas. It will also be important to take action to tackle global climate change, and to build greater awareness of the threats to corals (1) (6) (8). Techniques for artificially growing corals or for storing their eggs and sperm may also play a role in coral conservation in the future (1).

Due to the severity of the effects of climate change and ocean acidification on corals, it will be important to assess the conservation status of Platygyra sinensis again in the near future, to ensure that it has not become endangered (1).

Find out more about corals and their conservation:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (December, 2012)
    http://www.iucnredlist.org/
  2. CITES (December, 2012)
    http://www.cites.org/
  3. Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
  4. Dai, C.F. and Horng, S. (2009) Scleractinia Fauna of Taiwan. II. The Robust Group. National Taiwan University Press, Taipei, Taiwan.
  5. Veron, J.E.N. (1993) Corals of Australia and the Indo-Pacific. University of Hawaii Press, Honolulu, Hawaii.
  6. Miththapala, S. (2008) Coral Reefs. Coastal Ecosystems Series (Volume 1). Ecosystems and Livelihoods Group Asia, IUCN, Colombo, Sri Lanka. Available at:
    http://data.iucn.org/dbtw-wpd/edocs/2008-012.pdf
  7. Babcock, R.C., Bull, G.D., Harrison, P.L., Heyward, A.J., Oliver, J.K., Wallace, C.C. and Willis, B.L. (1986) Synchronous spawnings of 105 scleractinian coral species on the Great Barrier Reef. Marine Biology, 90: 379-394.
  8. Wilkinson, C. (2008) Status of Coral Reefs of the World: 2008. Global Coral Reef Monitoring Network and Reef and Rainforest Research Center, Townsville, Australia. Available at:
    http://www.gcrmn.org/status2008.aspx
  9. Carpenter, K.E. et al. (2008) One-third of reef-building corals face elevated extinction risk from climate change and local impacts. Science, 321: 560-563.