''Eusmilia'' is a genus of

stony coral Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mo ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Meandrinidae The Meandrinidae are a family of stony corals. The name comes from the Greek, ''maiandros'' meaning "meandering", referring to the miniature, winding valleys found between the corallites. Fossil corals in this family have been found dating back t ...

. It is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus represented by the

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 ...

''Eusmilia fastigiata'', commonly known as the smooth flower coral. It is found on reefs in the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

Description

Smooth flower coral is a

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...

species that grows to about across. It forms a low mound of stony calcium carbonate, the surface of which is covered with tubular projections, the corallites, in groups of one to three. The polyps protrude from these and are either round or oval, with the oval form being more common at moderate depths. They are large and widely spaced and are connected by a layer of translucent, jelly-like

mesoglea Mesoglea refers to the extracellular matrix found in cnidarians like coral or jellyfish that functions as a hydrostatic skeleton. It is related to but distinct from mesohyl, which generally refers to extracellular material found in sponges. Desc ...

tissue called

coenosarc In corals, the coenosarc is the living tissue overlying the stony skeletal material of the coral. It secretes the coenosteum, the layer of skeletal material lying between the corallites (the stony cups in which the polyps sit). The coensarc is comp ...

which covers the surface of the carbonate skeleton. During the day they are retracted back into the cup-shaped corallites. These have large smooth-edged ridges called

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five c ...

, and the polyps have corresponding grooves at their base. At night, the polyps stretch out their translucent white tentacles to feed and the coral "flowers". This coral is usually cream, yellow or pale brown, often with a green or pink tinge.

Distribution and habitat

Smooth flower coral is found in the Caribbean, the Gulf of Mexico, the Bahamas and southern Florida, at depths down to about though it is commonest between . It is found on both the back and the front edges of reefs and is sometimes overhung by larger corals. It is listed as being critically endangered by the IUCN Red List of Threatened Species

Biology

The polyps remain retracted in the skeleton during the day but extend at night to feed. The tentacles search for

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

and small invertebrates which are transferred to the mouth. Another major source of energy is the result of the symbiotic dinoflagellates which live within the coenenchyme and which produce nutrients by photosynthesis. The coral benefits from the carbohydrates produced and the algae use the coral's nitrogenous waste products.

Reproduction

Reproduction in corals takes place when gametes are released into the water. The fertilized

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

develops into a

planula A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores. Some groups of Nemerteans also produce larvae that are very similar to the planula, which ...

larva which forms part of the zooplankton and drifts with the current. After passing through a number of larval stages this settles on the sea bed and undergoes metamorphosis into a polyp. The base of this secretes the calcium carbonate skeleton and the polyp founds a new colony, producing new polyps by budding.

References

{{Taxonbar, from1=Q13630238, from2=Q2785489 Scleractinia genera Monotypic cnidarian genera Meandrinidae