Astreopora is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of stony corals in the Acroporidae

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 as staghorn corals and are grown in aquaria by reef...

 family. Members of the genus are commonly known as star corals and there are about thirteen 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...

.

Description

Members of this genus mostly form dome-shaped or rounded heads but sometimes have leaflike extensions, be encrusting or form plates, vases and branches. They are much larger than members of the genus Montipora

Montipora

Montipora is a genus of small polyp stony coral in the phylum Cnidaria. Depending on the species and location, Montipora may grow as plates or ridges, appearing to some as a bowl or flower. Undisturbed, the plates expand radially and may encrust over surrounding rocks, shells or debris...

. They have a wide range of colours including yellow, brown, green, pink and blue but the most common are whitish-blue. The corallites are distinct and separate, sometimes raised on cones and sometimes depressed, up to four millimetres across and round in cross-section. The skeleton is porous with the coenosteum having a net-like appearance. The coral appears rough-textured because of tiny spines that cover the surface between the corallites. The septa are poorly developed giving corals of this genus the appearance of being filled with holes.

Distribution

Members of this genus occur in the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

, the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and the western Pacific

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. They are widespread but not particularly common and are a reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

 building species. They are found in a range of environments including shallow or muddy waters and deeper areas of the reef where plating forms are most common. In shallow water they are inconspicuous and are never dominant. They may form heads of up to two metres in diameter and in deeper waters they may be much more common.

Ecology

The porous skeleton of these corals provide a home to a variety of polychaete

Polychaete

The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...

 worms that weaken the calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

 structure by tunnelling into it.

Several species of coral-inhabiting barnacle

Barnacle

A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...

s are associated with Astreopora. In fact, Hiroa stubbingsi and two species of Cionophora seem to occur nowhere else. In the case of H. stubbingsi, which has a primitive wall and a relatively unspecialised operculum

Operculum

Operculum may refer to:*Operculum , a stiff structure resembling a lid or a small door that opens and closes**Operculum , a lid on the shell of some gastropods**Operculum , a lid on the orifice of some bryozoans...

, this may be because it is not equipped to occupy other corals, but the Cionophora species are smaller and it is an enigma why they are not found elsewhere.

Species

Known species include:

• Astreopora cucullata - Lamberts, 1980
• Astreopora expansa
• Astreopora explanata - Veron, 1985
• Astreopora gracilis - Bernard, 1896
• Astreopora incrustans - Bernard, 1896
• Astreopora lambertsi - Moll and Best, 1984
• Astreopora listeri - Bernard, 1896
• Astreopora macrostoma - Veron and Wallace, 1984
• Astreopora moretonensis - Veron and Wallace, 1984
• Astreopora myriophthalma - (Lamarck, 1816)
• Astreopora ocellata - Bernard, 1896
• Astreopora randalli - Lamberts, 1980
• Astreopora scabra
• Astreopora suggesta - Wells, 1954