Alcyoniidae is a family of leathery or soft corals

Alcyonacea

The Alcyonacea, or the soft corals are an order of corals which do not produce calcium carbonate skeletons. Soft corals contain minute, spiny skeletal elements called sclerites. Aside from their scientific utility in species identification, sclerites give these corals some degree of support and...

 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,...

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Description

A colony of leathery coral is stiff, hard and inflexible. It is composed of tiny polyps projecting from a shared leathery tissue. Members of the family may have two kinds of polyps; the autozooids have long trunks and eight tiny branched tentacles and project from the shared leathery tissue while the siphonozooids remain below the surface and pump water for the colony. They appear as tiny hollows or mounds among the taller autozooids. Different genera have different proportions of these two kinds of polyps. The autozooids only emerge when the colony is fully submerged.

Distribution and habitat

Leathery corals occur globally in temperate and tropical seas. They are often pioneer reef species and are found in wave-exposed areas of reef crests, less turbid waters in lagoons, on steep slopes, under overhangs and at depths of thirty metres or even deeper.

Biology

Leathery coral polyps include endosymbiotic

Endosymbiont

An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis...

 algae called zooxanthallae. The algae undergo 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...

 and produce sugars from sunlight. This food is shared with the host, which itself provides the algae with minerals and shelter. Periodically, the surface layer of the leathery tissue is shed. This seems to be a mechanism for ridding the colony of unwanted algal growth.

In a study on the Great Barrier Reef

Great Barrier Reef

The Great Barrier Reef is the world'slargest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres over an area of approximately...

, it was found that the population of these corals was very stable. There was little predation, low rates of growth, reproduction and mortality, few new colonies came into existence and few disappeared over a three year period.

Genera

• Acrophyton
• Alcyonium
• Anthomastus
• Bellonella
• Cladiella
• Dampia
• Dimorphophyton
• Eleutherobia
• Inflatocalyx
• Lobophytum
• Lohowia
• Malacacanthus
• Minabea
• Notodysiferus
• Paraminabea
• Parerythropodium
• Protodendron
• Pseudoanthomastus
• Rhytisma
• Sarcophyton
• Sinularia
• Verseveldtia