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 ...
of stony
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 ...
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 ...
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 ...
. It is a
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 out ...
building coral living in shallow water and adopts different forms depending on the water conditions where it is situated. It is found in the Western Indo-Pacific Ocean as far east as Australia.
Description
''Isopora palifera'' can be encrusting, or massive, form columnar branches or parallel ridges of blade-like branches. The shape adopted is much dependent on how much water movement there is at its site of growth; it is encrusting in a strong current or on the seaward side of a reef and is more branching in calm, still conditions. The branches are in diameter and up to long. Each branch has several axial
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 up to in diameter. The radial corallites are cylindrical, large and close together or touching, and project from the branches by up to . Each has a distinct, large irregularly shaped opening near the tip. The colour of this coral is greenish, creamy or pale brown. This colour comes from minute
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 ...
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 known as zooxanthellae which live within the tissues of the coral polyps. 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 c ...
algae use sunlight to create organic compounds and the coral is able to use these to provide part of its nutritional needs. Fluorescent granules of pigment are present in the tissues and these are in greater concentrations in individuals growing in high-light environments. ''Isopora palifera'' closely resembles '' Isopora cuneata'', and often has similar forms of growth, but ''I. cuneata'' mostly occurs in more eastern parts of the Pacific and in shallower water, and the holes in its conical-shaped radial corallites are circular in outline.
Distribution
''Isopora palifera'' is found in the Indo-Pacific Ocean. Its range extends from South Africa and Madagascar to East Africa, Aldabra and Chagos, India, China, Japan, Indonesia and Australia. It is the commonest species of coral in the northern part of the
Great Barrier Reef
The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over over an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland, ...
. It is a reef building coral and is found subtidally on reef flats, edges walls and slopes. ''Isopora palifera'' first appears in the fossil record in Papua New Guinea in the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58black band disease and
white band disease
White band disease is a coral disease that affects acroporid corals and is distinguishable by the white band of exposed coral skeleton that it forms. The disease completely destroys the coral tissue of Caribbean acroporid corals, specifically e ...
.
In a study in Taiwan, it was found that two different algal symbionts, '' Symbiodinium'' phylotypes C and D, were associated with the coral. One or both were present at any one time, the proportion of each fluctuating with the time of year, the sea water temperature and changing light levels. It is when neither is present, as may happen when the water temperature rises too high, that
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 ...
is caused, and when this happens, the coral is prone to damage, disease, and death.