''Acropora arabensis'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of acroporid coral native to the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

and was originally described by Gregor Hodgson and Kent Carpenter in 1995. It is a locally common species usually found in upper

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

slopes and

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

s, most commonly between 3 to 5 m depth. Like other species in the

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 ...

genus, it is susceptible to

coral bleaching Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae (dinoflagellates that are commonly referred to as alg ...

. It is classified as "Near Threatened" by the

IUCN Red List 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 biol ...

and population numbers are currently decreasing.

Description

''Acropora arabensis'' has a digitate skeletal structure with infrequently dividing branches which taper at the ends. Its surface has dome-shaped axial

corallite A corallite is the skeletal cup, formed by an individual stony coral polyp, in which the polyp sits and into which it can retract. The cup is composed of aragonite, a crystalline form of calcium carbonate, and is secreted by the polyp. Corallit ...

s and thick-walled, strongly appressed radial corallites. Axial and radial corallites form two synapticular rings. Corallite size decreases towards the ends of the branches. Colonies that form in deeper, more protected reef areas have a tendency to form more tubular radial corralites among immersed ones. Lamellar

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...

are moderately well-developed and almost extend to the center with a radius about one half of calice radius.

Distribution

To date, ''Acropora arabensis'' is only known to live natively off the coast of

Kuwait Kuwait (; ar, الكويت ', or ), officially the State of Kuwait ( ar, دولة الكويت '), is a country in Western Asia. It is situated in the northern edge of Eastern Arabia at the tip of the Persian Gulf, bordering Iraq to the nort ...

in the

Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Persis, Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a Mediterranean sea (oceanography), me ...

where the species was initially discovered. Additional specimens have been discovered in the southern

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...

and off the northern

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

coast.

Field identification

It is pale brown to grey in color. Similar in appearance, ''

Acropora ocellata ''Acropora humilis'', also known as finger coral, is a species of acroporid coral found in the Gulf of Aden, the Red Sea, the northern and southwestern Indian Ocean, Australia, the central Indo-Pacific, Japan, southeast Asia, the East China S ...

'' has longer branches and more elongate radial corallites. It can be differentiated from ''

Acropora clathrata ''Acropora clathrata'', commonly known as lattice table coral is a species of stony corals belonging to the family Acroporidae. They are a zooxanthellate coral, which are generally found in fringing reefs, sheltered reefs and back reef habitats, b ...

'' by its tree-like structure and its strongly appressed, regularly distributed corallites.

References

{{Taxonbar, from=Q3944344 Cnidarians of the Pacific Ocean Marine fauna of Asia Marine fauna of Oceania Vulnerable fauna of Oceania Acropora Vulnerable fauna of Asia Vulnerable fauna of Australia Animals described in 1995