''Acropora horrida'' is a species of acroporid

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

that was first described by

James Dwight Dana James Dwight Dana Royal Society of London, FRS FRSE (February 12, 1813 – April 14, 1895) was an American geologist, mineralogist, volcanologist, and zoologist. He made pioneering studies of mountain-building, volcano, volcanic activity, and the ...

in 1846. Found in tropical, shallow reefs in marine environments, it occurs near

fringing reef A fringing reef is one of the three main types of coral reef. It is distinguished from the other main types, barrier reefs and atolls, in that it has either an entirely shallow backreef zone (lagoon) or none at all. If a fringing reef grows direc ...

s around

turbid Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids can ...

water, at depths of . It is listed as a

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

on 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 it is thought to have a decreasing population. It is not common and found over a large area, and is listed under CITES Appendix II.

Description

''Acropora horrida'' forms in colonies, which are mainly open branched. It is light blue, dark blue, light yellow, or brown in colour, with white or pale blue polyps. The main branches contain an unorganised structure of branchlets, based on examples in water showing turbidity. However, in clear water, the branchlets are short, making the structure appear bristly. The corallites are rough and irregularly placed, and tentacles enlarge during the day. There are no similar species within genus ''Acropora''. It is found in marine, tropical, shallow reefs, mainly in turbid water near fringing reefs. It also occurs in shallow lagoons and sand slopes, and is found at depths of between . It is believed to survive for more than ten years, and reaches maturity at between three and eight. It is composed of

aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including prec ...

(calcium carbonate).

Distribution

''Acropora horrida'' occurs over a large area but is not common; the Red Sea, the Indian Ocean, the Gulf of Aden, 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 ...

, the Indo-Pacific, the East China Sea, Japan, and Southeast Asia, the Line Islands, Indonesia, and Palau. Recently, numbers for the species have declined in the Great Barrier Reef, Papua New Guinea, Kimbe Bay, and Orpheus Island. There is no specific population data for this species, but numbers have been observed to be declining in some locations, and are believed to be decreasing in others. It is not very resistant to disease and bleaching by sea temperature increases, and is affected by being prey to ''Acanthaster planci'', climate change, fishing, human activity and industry, and pollution. It exists in temperatures between , and first appeared between 5.33 and 2.59

myr The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

ago. It is listed as a vulnerable species on the IUCN Red List, and is also listed under CITES Appendix II.

Taxonomy

It was first described by James Dwight Dana in 1846 as ''Madrepora horrida'' in Fiji.

References

{{Taxonbar, from=Q3947988 Acropora Cnidarians of the Indian Ocean Cnidarians of the Pacific Ocean Fauna of the Red Sea Marine fauna of Asia Marine fauna of Oceania Marine fauna of Southeast Asia Marine fauna of Western Asia Anthozoa of Australia Vulnerable fauna of Asia Vulnerable fauna of Australia Vulnerable fauna of Oceania Corals described in 1846 Taxa named by James Dwight Dana