''Favites complanata'' 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 ...

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 ...

in the

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

Merulinidae Merulinidae is a family of reef-building stony corals. Characteristics All the genera in this family are colonial, reef-building corals. Skeletal structures are similar to those of Faviidae but are highly fused, without paliform lobes. The vall ...

, sometimes known as the larger star coral. It is native to the Indo-Pacific region and its range extends from the Red Sea and Indian Ocean to the western and central Pacific Ocean. This is an uncommon species of coral and seems to be decreasing in abundance, and the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has rated its conservation status as being "

near threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

Description

colony In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the ''metropole, metropolit ...

of ''Favites complanata'' forms a solid dome or mound. The

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 (stony cups in which the polyps sit) are large and somewhat angular, with thick, rounded walls between them. The calyces are in diameter. The

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 ...

(stony ridges inside the corallites) are in two whorls and each has four or five teeth. The paliform lobes are distinct on the first whorl of septa and the columella at the centre of the corallite is large. The stony ridges, now known as costae, continue between the corallites and often form three-pointed stars where the walls of three corallites join. This coral is usually a dull brown colour, the oral discs of the polyps sometimes being a contrasting green or grey colour.

Distribution

''Favites complanata'' is found in the western and central Indo-Pacific. Its range extends from Madagascar, the Seychelles and the Red Sea to India, the Maldives, Australia, Japan and the East China Sea. It is present in various reef habitats at depths down to about .

Ecology

The polyps of ''Favites complanata'' expand and extend their

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s to catch

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

, but much of the nutritional requirements of this coral are met by the

zooxanthellae 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 ...

housed within its tissues. These

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

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s use

photosynthesis 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 i ...

to create organic molecules. In adverse conditions, such as when the coral is stressed by high temperatures, the zooxanthellae may be expelled and the coral becomes

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and white. Bleaching occurs in this species when the water temperature rises above .

References

{{Taxonbar, from=Q3952142 Merulinidae Corals described in 1834 Taxa named by Christian Gottfried Ehrenberg