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an order of marine coelenterates of the class Anthozoa. They are predominantly colonial forms that are attached to the sea floor. Solitary madreporic corals are up to 25 cm across (Fungia), and separate individuals of the colonial forms are from 1 mm to 3 cm in diameter. Colonies can extend for several meters and have various forms. The basic part of the colony is the calcareous skeleton. There are approximately 2,500 species.
Madreporic corals are found in all the oceans of the world but are distributed very unevenly. They live mostly in clean water saturated with oxygen, in seas with normal salinity, and at a temperature no lower than 20.5°C. For this reason, madreporic corals grow largest in the upper layers (no deeper than 50 m) of the tropical waters of the Pacific and Indian oceans and the Caribbean Sea. In these regions madreporic corals and bryozoans, mollusks, calcareous algae, and some other marine organisms form huge colonies, called coral reefs. The vivid colors of reef-forming madreporic corals are provided by pigments and symbiotic one-celled algae living in their tissues. The crevices of the reef are inhabited by other coelenterates, worms, mollusks, crustaceans, echinoderms, and fish; many of these organisms feed on the madreporic corals. At greater depths (to 6,000 m) only some small solitary madreporic corals are found.
The seas of the temperate and polar latitudes have only a few species of Madreporaria, which form large colonies only rarely (for example, in the Norwegian Sea colonies of Lophelia are found at a depth of about 200 m). The seas of the USSR have only noncolonial forms: Flabellum in the Barents Sea and Caryophyllia in the seas of the Far East. Dead madreporic corals form deposits of organogenic limestone, which is used to obtain sawed stone, wall blocks, and raw material for the production of lime and pigments. Colonies of madreporic corals or parts of colonies are used as table ornaments.
D. V. NAUMOV