''Ctenella'' is a monotypic genus of

stony coral Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mo ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Euphylliidae. It is represented by a single species, ''Ctenella chagius''. These corals are massive in size with meandering valleys between the calyces which have solid, non-porous walls and fine, evenly spaced, solid septae.Family Meandrinidae
Classification of Scleractinian (Stony) Corals. Retrieved 2012-11-10. They are found in 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 t ...

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''; ...

and

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

. It forms solid, smooth hemispherical domes and is found in the Indian Ocean in the vicinity of the

Chagos Archipelago The Chagos Archipelago () or Chagos Islands (formerly the Bassas de Chagas, and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives arch ...

Description

''Ctenella chagius'' is a massive, hemispherical,

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 au ...

coral with a fissured surface and brain-like appearance. The individual polyps that secrete the stony skeleton project from stony cups called corallites arranged in rows in long meandering valleys. The width between the solid ridges on either side is about with the valleys being about deep. The fine

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 c ...

that radiate from the corallites are closely packed and evenly spaced, some continuing upwards and over the ridges.Family Meandrinidae
Classification of Scleractinian (Stony) Corals. Retrieved 2012-11-20. This coral is a pale brown colour and can grow to a metre (yard) in diameter. It is a

zooxanthellate Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''Sy ...

coral and has symbiotic unicellular dinoflagellate algae living within its tissues.

Distribution

''Ctenella chagius'' is found around the Chagos Islands. It is found in

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'') ...

s and on

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 o ...

slopes at depths of up to .

Status

''Ctenella chagius'' is listed as being "

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

" in the IUCN Red List of Threatened Species. The size of its population is unknown but the reefs on which it lives are being degraded at a faster rate than it is likely to be able to establish new colonies. It is very 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 a ...

and coral diseases, both of which are on the increase as sea temperatures rise. There are also threats to the coral from human activities but the Chagos Islands are now part of the

Chagos Marine Protected Area The Chagos Marine Protected Area, located in the central Indian Ocean in the British Indian Ocean Territory of the United Kingdom, is one of the world's largest marine protected areas, and one of the largest protected areas of any type (land or se ...

which should provide a measure of protection for this coral.

References

{{Taxonbar, from1=Q5191613, from2=Q3330213 Scleractinia genera Euphylliidae Animals described in 1928 Monotypic cnidarian genera