Fleshy artichoke coral  (Acanthastrea maxima)

Classified as Near Threatened (NT) on the IUCN Red List (1) and listed on Appendix II of CITES (2).

The fleshy artichoke coral is a little-known, rare coral described as recently as 1998 (1). The most distinguishing features of this species are its heavy, toothed septa and thick, fleshy walls (3) (4). Like other colony-forming corals, colonies of the fleshy artichoke coral are composed of numerous small polyps, soft-bodied animals related to anemones. Each polyp bears numerous tentacles that direct food into a central mouth, where it is digested in a sac-like body cavity. One of the most remarkable and ecologically important features of corals is that the polyps secrete a hard skeleton, called a ‘corallite’, which over successive generations contributes to the formation of a coral reef. The coral skeleton forms the bulk of the colony, with the living polyp tissue comprising only a thin veneer. Living colonies of the fleshy artichoke coral tend to be green, grey or brown in colour (3). 

The fleshy artichoke coral is found in the Gulf of Aden, north-western Indian Ocean and Arabian Gulf (1).

This coral prefers relatively deep, turbid waters with sandy substrates and low light (1) (4).

Like many coral species, the tissue of the fleshy artichoke coral contains large numbers of single-celled algae called zooxanthellae. The coral and the algae have a symbiotic relationship in which the algae gain a safe, stable environment within the coral's tissues, while the coral receives nutrients produced by the algae through photosynthesis. By harnessing the sun's energy in this way, corals are able to grow rapidly and form vast reef structures, but are constrained to live near the water surface. While, on average, zooxanthellate coral can obtain around 70 percent of its nutrient requirements from zooxanthellae photosynthesis, the coral may also feed on zooplankton (3). 

With an estimated 20 percent of the world’s coral reefs already destroyed, the fleshy artichoke coral faces many of the threats that are affecting coral reefs globally (5) (6). Worldwide there is increasing pressure on coastal resources resulting from human population growth and development. There has been a significant increase in domestic and agricultural waste in the oceans, poor land-use practices that result in an increase in sediment running on to the reefs, and over-fishing, which can have ‘knock-on’ effects on the reef (6). However, the major threat to corals is global climate change, with the expected rise in ocean temperatures increasing the risk of coral ‘bleaching’, in which the stressed coral expels its zooxanthellae, often resulting in the death of the coral. Climate change may also lead to more frequent, severe storms, which can damage reefs, and rising carbon dioxide levels may make the ocean increasingly acidic. Such stresses can also make corals more susceptible to disease, parasites and predators, such as the crown-of-thorns sea star (Acanthaster planci) (5) (6) (7).

In addition to being listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which makes it an offence to trade this species without a permit, the fleshy artichoke coral also forms part of the reef community in numerous marine protected areas (1) (2). To specifically conserve this coral, recommendations have been made for a raft of studies into various aspects of its biology, population status, habitat and threats to its survival (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

Environment Agency - Abu Dhabi is a principal sponsor of ARKive. EAD is working to protect and conserve the environment as well as promoting sustainable development in the Emirate of Abu Dhabi.

For further information on the conservation of coral reefs, see:

• Reef Check:
  http://www.reefcheck.org/
• Coral Reef Alliance:
  http://www.coral.org/