Acropora

Acropora

Overview


Acropora is a genus of scleractinia
Scleractinia
Scleractinia, also called stony corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian...

n coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 in the Phylum Cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...

. Some of its species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are known as table coral, elkhorn coral
Elkhorn coral
Elkhorn coral is considered to be one of the most important reef-building corals in the Caribbean. This species of coral is structurally complex with many large branches. The coral structure closely resembles that of elk antlers. These branches create habitats for many other reef species such as...

 and staghorn coral
Staghorn coral
The Staghorn coral is a branching coral with cylindrical branches ranging from a few centimetres to over two metres in length and height. It occurs in back reef and fore reef environments from 0 to 30 m depth. The upper limit is defined by wave forces, and the lower limit is controlled by...

. There are currently 149 described species. Acropora is one of the major reef building corals responsible for building the immense calcium carbonate substructure that supports the thin living skin of a reef.

Depending on the species and location, Acropora may grow as plates or slender or broad branches.
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Encyclopedia


Acropora is a genus of scleractinia
Scleractinia
Scleractinia, also called stony corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian...

n coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 in the Phylum Cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...

. Some of its species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are known as table coral, elkhorn coral
Elkhorn coral
Elkhorn coral is considered to be one of the most important reef-building corals in the Caribbean. This species of coral is structurally complex with many large branches. The coral structure closely resembles that of elk antlers. These branches create habitats for many other reef species such as...

 and staghorn coral
Staghorn coral
The Staghorn coral is a branching coral with cylindrical branches ranging from a few centimetres to over two metres in length and height. It occurs in back reef and fore reef environments from 0 to 30 m depth. The upper limit is defined by wave forces, and the lower limit is controlled by...

. There are currently 149 described species. Acropora is one of the major reef building corals responsible for building the immense calcium carbonate substructure that supports the thin living skin of a reef.

Anatomy and distribution


Depending on the species and location, Acropora may grow as plates or slender or broad branches. Like other corals, Acropora corals are colonies of individuals known as polyps, which are about 2 mm across and share tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 and a nerve net
Nerve net
A nerve net is a type of simple nervous system that is found in members of the cnidaria, ctenophora, and echinodermata phyla. Nerve nets consist of interconnected neurons lacking a brain or any form of cephalization. This nervous system allows cnidarians to respond to physical contact. They may...

. The polyps can withdraw back into the coral in response to movement or disturbance by possible predators, but when undisturbed they protrude slightly. The polyps typically extend further at night to help capture plankton and dissolved organic matter from the water.

Acropora is most common in shallow reef environments with bright light and moderate to high water motion. Many small reef fishes live near Acropora colonies and retreat into the thicket of branches if threatened.

Threats



These corals have zooxanthellae, symbiotic algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 that live in the corals' cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

s and produce energy for the animals through photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

. Environmental destruction has led to a dwindling of populations of Acropora, along with other coral species. Acropora is especially susceptible to bleaching when stressed. Bleaching is due to the loss of the coral's zooxanthellae, which are a golden-brown color. Bleached corals are stark white and may die if new zooxanthellae cannot be assimilated. Common causes of bleaching and coral death include pollution, abnormally warm water temperatures, increased ocean acidification
Ocean acidification
Ocean acidification is the name given to the ongoing decrease in the pH and increase in acidity of the Earth's oceans, caused by the uptake of anthropogenic carbon dioxide from the atmosphere....

, sedimentation, and eutrophication.

Reef-keeping



Most Acropora are brown or green but a few are brightly colored and those rare corals are prized by aquarists. Captive propagation of Acropora is widespread in the reef-keeping community. Given the right conditions, many Acropora species grow quickly and individual colonies can exceed 1 meter across in the wild. In a well maintained reef aquarium, finger-sized fragments can grow into basketball-sized colonies in 1 to 2 years. Captive specimens are steadily undergoing changes due to selection which enable them to thrive in the home aquarium. In some cases, fragments of captive specimens are used to repopulate barren reefs in the wild.

Acropora species are challenging to keep in a home aquarium. They require bright light, stable temperatures, and turbulent water. Providing these elements can be too expensive for the average hobbyist.

A common pest in reef aquarium
Reef aquarium
A reef aquarium or reef tank is an marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the coral reef environment...

s are the Acropora Eating Flatworm
Acropora Eating Flatworm
Acropora Eating Flat Worms are a kind of Platyhelminthes that pest the genus Acropora in reef aquariums....

.

Further reading

  • Reyes-Bermudez A. et al. 2009. Differential expression of three galaxin-related genes during settlement and metamorphosis in the scleractinian coral Acropora millepora. BMC Evolutionary Biology 2009, 9:178.

  • Shinzato, C., Shoguchi, E., Kawashima, T., Hamada, M., Hisata, K., Tanaka, M., Fujie, M., et al. 2011. Using the Acropora digitifera genome to understand coral responses to environmental change. Nature, advance online publication. doi:10.1038/nature10249

External links

  • International Reefers. A reef aquarium
    Reef aquarium
    A reef aquarium or reef tank is an marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the coral reef environment...

     Internet forum
    Internet forum
    An Internet forum, or message board, is an online discussion site where people can hold conversations in the form of posted messages. They differ from chat rooms in that messages are at least temporarily archived...

    .