''Acropora cytherea'' is a stony coral which forms horizontal table like structures. It occurs in the Indo-Pacific Ocean in areas with little wave action, favouring back reef environments from depth.

Description

''Acropora cytherea'' is a

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 a ...

species of coral that grows in large horizontal plates. These are formed of many tiny branchlets growing vertically or at an angle and others growing horizontally to extend the colony. They may branch and link together and near the centre the plates may become a solid mass of joined branchlets. The surface of the coral is covered by a thin layer of living tissue. This has a rough surface and contains '' zooxanthella'',

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

, unicellular,

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

algae. These give the coral its cream or pale brown colour (occasionally pale blue). The calcium carbonate skeleton is secreted by many small polyps which are joined together through an interconnecting network of channels inside the skeleton. At night, and sometimes during the day, the polyps protrude from the skeleton and extend their tentacles to feed. At other times, they contract back into the safety of the skeleton. In older specimens, particularly those exceeding in diameter, the regular structure sometimes breaks down near the centre and there are growth anomalies. It has been found that these are not deleterious to the survival of the coral and may be caused by stress factors such as raised sea temperatures.

Distribution and habitat

''Acropora cytherea'' is one of the most plentiful members of the genus ''

Acropora ''Acropora'' is a genus of small polyp stony coral in the phylum Cnidaria. Some of its species are known as table coral, elkhorn coral, and staghorn coral. Over 149 species are described. ''Acropora'' species are some of the major reef corals r ...

''. It is found in the Indo-Pacific Ocean from the Red Sea and the east coast of Africa to India, the China Sea,

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

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, Micronesia and Hawaii. It is found below low tide mark in clear shallow water with little wave action, in lagoons and upper reef slopes and back reef slopes.

Ecology

Several small

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

s are obligate associates of corals, feeding on coral tissues but protecting the coral from attack by predators such as the

crown-of-thorns starfish The crown-of-thorns starfish (frequently abbreviated to COTS), ''Acanthaster planci'', is a large starfish that preys upon hard, or stony, coral polyps (Scleractinia). The crown-of-thorns starfish receives its name from venomous thorn-like spine ...

. One of these, '' Cymo melanodactylus'', lives in association with ''Acropora cytherea'' but its low numbers (fewer than three per coral) mean that its

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suffers little harm. In the Chagos Archipelago these crabs have shown a change in their behaviour and have been found in large numbers infesting diseased and dying corals. In 2010 in the Archipelago, infestations of over 45 of these crabs were found on individual heads of ''A. cytherea'' exhibiting dead and dying tissue. The crabs were in close proximity to the damaged tissues but it was unclear whether the crabs were the original cause of the damage or whether they had moved in to exploit the already dying tissues.

Status

''Acropora cytherea'' is considered by the

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

to be of " Least concern". This is because it has a wide range and in many locations it is one of the more abundant reef building species. One of the threats it faces is from the voracious crown-of-thorns starfish which has become more abundant in the Pacific and Indian Oceans since about 1970 and has periodical breakouts when its numbers increase dramatically. Apart from predators, corals in general are at risk from rising sea temperatures, violent storms, ocean acidification, bleaching and coral diseases.

References

{{Taxonbar, from=Q3657950 Acropora Corals described in 1846