''Acropora pulchra'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

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 ...

staghorn

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 secre ...

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 ...

Acroporidae Acroporidae is a family of small polyped stony corals in the phylum Cnidaria. The name is derived from the Greek ''"akron"'' meaning "summit" and refers to the presence of a corallite at the tip of each branch of coral. They are commonly known a ...

. It is found on the back fringes of reefs in shallow water in the western Indo-Pacific Ocean. The oldest fossils of this species date back to the

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

Description

The stony skeleton of ''Acropora pulchra'' takes on various forms. It is a branching species, sometimes being tree-like and forming thickets and in other locations forming tangled colonies with level upper surfaces. The branches are up to in diameter and up to long. Often the whole colony spreads horizontally and is no more than thick. The growth habit largely depends on where the coral is growing in relation to the tide levels. The polyps protrude from little cup-shaped depressions called

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 which are widely spaced on the branches and which have elongated lower lips. The colour of this coral varies from blue to various shades of brown, often with pale blue tips to the branches.

Distribution and habitat

''Acropora pulchra'' is found in the western Indo-Pacific region, its range extending from the Gulf of Aden to Southeast Asia, Japan, the East China Sea and Australia. It chiefly grows at depths which range from on back reef fringes and flats and in reef

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, often growing among the closely related coral species '' Acropora aspera''.

Biology

The polyps of ''Acropora pulchra'' extend their tentacles to catch plankton. However, much of the nutrition the coral receives comes from the symbiotic

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 '' ...

found in the tissues. These

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 ...

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 produce energy when exposed to sunlight and the coral makes use of this. ''Acropora'' spp. corals are slow-growing and flourish in clear water. They are particularly sensitive to sediment, pollution and algal blooms, which cloud the water and reduce the amount of incoming sunlight. Nor do they like temperatures outside the range to . If the sea gets too hot they may expel the zooxanthellae and this causes

bleaching Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...

of the coral. ''Acropora pulchra'' synchronizes its reproductive activities with the phase of the moon so that all the corals in one locality spawn on the same couple of days, although the date varies between the northern and southern hemispheres and different parts of the coral's range. It can also reproduce asexually when broken fragments of coral come to rest in positions where they can establish themselves. Experiments have been carried out on the feasibility of transplanting this coral to other suitable habitats where it is not native. These trials were successful but transplants were adversely affected by excess sedimentation and tended to grow more slowly than control corals.

Status

The IUCN Red List of Threatened Species lists ''Acropora pulchra'' as being of "

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. Th ...

" because it has a large range and although often uncommon, it is the dominant species in some localities. The chief threats it faces are from the general destruction of coral reefs,

ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxi ...

, raised sea temperatures, and coral diseases. 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 ...

feeds preferentially on ''Acropora'' species corals, and it sometimes has sudden, unexpected increases in population which may threaten this coral.

References

{{Taxonbar, from=Q4666951 Acropora Corals described in 1891