Branched sandpaper coral (Psammocora contigua)

Also known as: dark green contigua, green stony pillar coral, pillar coral
GenusPsammocora (1)

The branched sandpaper coral is classified as Near Threatened (NT) on the IUCN Red List (1) and listed on Appendix II of CITES (2).

The colonies of the branched sandpaper coral (Psammocora contigua) grow in a variety of shapes depending on water movements, variously forming a mixture of flattened branches, columns, irregularly-shaped nodules, fused plates and branches, or even sometimes occurring as free-living, mobile balls (3) (4) (5) (6). Colonies are usually pale to dark greyish-brown in colour (3) (4) (5) (6), and may reach about 10 centimetres in height (5) (7) and up to 50 centimetres in diameter (5). Like all corals, the colonies of the branched sandpaper coral are composed of numerous tiny, soft-bodied, anemone-like animals called polyps, which in many corals secrete a hard skeleton, with the individual skeleton of a polyp being known as a ‘corallite’ (3). In the branched sandpaper coral, the inward projections of the corallite (the ‘septa’) have granulated margins (3) (4) (5), which may give this coral its common name, as it is reported to have a coarse, sandpaper-like surface (7). However, the fine, shallow corallites generally give the colony a smooth outward appearance (3) (4) (5) (6).

The branched sandpaper coral is widespread throughout the Indian Ocean and the western and central Pacific Ocean, as well as occurring in the Red Sea, Gulf of Aden and Arabian Gulf (1) (3) (4) (5) (6).

The branched sandpaper coral is common in a range of shallow reef environments, although it is usually found over a soft substrate (3) (4) (5) (6), generally to depths of around 30 metres (1).

The branched sandpiper coral is a zooxanthellate coral, obtaining most of its nutrients from microscopic algae, known as zooxanthellae, which live within its tissues. The zooxanthellae provide the coral with nutrients through photosynthesis, in return receiving a safe and stable environment in which to live (3) (8). The branched sandpaper coral is also able to supplement its diet with tiny zooplankton, caught using stinging cells on the numerous tentacles which surround the central ‘mouth’ of each polyp (3). In the branched sandpaper coral, the tentacles are usually only extended for feeding at night (3) (4).

Like other corals, the branched sandpaper coral is able to reproduce asexually in a process known as ‘budding’, in which polyps divide to form new polyps. Corals are also able to reproduce sexually, usually by releasing large numbers of sperm and eggs into the water column. The fertilised eggs develop into larvae, which eventually settle on the substrate and develop into polyps (3). Although little specific information is available for the branched sandpaper coral, other Psammocora species are reported to reproduce in this way, and to have two separate sexes (individuals in a colony are either all male or all female) (9).

Although it is common over a range of reef environments (1) (3) (4), the branched sandpaper coral is under threat from habitat loss, collection for the aquarium trade, and coral bleaching, in which elevated water temperatures cause the coral to expel its zooxanthellae, often resulting in death (1). Bleaching also leaves corals weakened and more vulnerable to disease, which is emerging as a serious threat to coral reefs worldwide (1) (11). Climate change is also a major threat, as it may lead to raised sea temperatures and so more severe bleaching events, as well as to more frequent, damaging storms, while increasing ocean acidity may also negatively affect corals. The branched sandpaper coral is also likely to be affected by many of the more localised threats to reefs, including sedimentation, pollution, destructive fishing practices, invasive species and increasing human development (1) (8) (10) (11).

Like all corals, the branched sandpaper coral 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 regulated (2). Parts of the branched sandpaper coral’s range also lie within Marine Protected Areas (1), although enforcement within these can often be poor (8), and currently less than half a percent of all marine habitats are officially protected (12). In addition to tackling global climate change, recommended conservation measures for corals include further research, population monitoring, research into coral diseases, reef restoration efforts, and the expansion of protected areas (1) (8) (11). With an estimated 20 percent of reefs already lost (11) and a third of reef-building corals at risk of extinction (10), the need to conserve coral reefs is now urgent if these important and diverse ecosystems are to survive (11).

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  1. IUCN Red List (November, 2010)
  2. CITES (November, 2010)
  3. Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
  4. Veron, J.E.N. (1993) Corals of Australia and the Indo-Pacific. University of Hawaii Press, Honolulu, Hawaii.
  5. Dai, C.F. and Horng, S. (2009) Scleractinia Fauna of Taiwan. II. The Robust Group. National Taiwan University Press, Taipei, Taiwan.
  6. Al Abdessalaam, T.Z. (2007) Marine Environment and Resources of Abu Dhabi. Environment Agency, Abu Dhabi.
  7. Coles, S.L. (1996) Corals of Oman. CYK Publications, Muscat, Oman. Available at:
  8. Miththapala, S. (2008) Coral Reefs. Coastal Ecosystems Series (Volume 1). Ecosystems and Livelihoods Group Asia, IUCN, Colombo, Sri Lanka. Available at:
  9. Glynn, P.W. and Colley, S.B. (2008) Survival of brooding and broadcasting reef corals following large scale disturbances: is there any hope for broadcasting species during global warming? Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008, Session number 11, 1: 368-372.
  10. 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.
  11. 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:
  12. UNEP: Fifty Key Facts about Seas and Oceans (November, 2010)