''Montastraea'' is a genus of colonial

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 ...

found in the Caribbean seas. It is the only genus in the monotypic family Montastraeidae and contains a single species, ''Montastraea cavernosa'', known as great star coral. It forms into massive boulders and sometimes develops into plates. Its polyps are the size of a human thumb and fully extend at night.

Description

Great star coral colonies form massive boulders and domes over 5 feet (1.5 m) in diameter in waters of shallow and moderate depths. In deeper waters, this coral has been observed growing as a plate formation. It is found throughout most reef environments, and is the predominant coral at depths of 40–100 feet (12.2-30.5 m). This coral occasionally has a fluorescent red or orange color during daytime; it has recently been suggested that this hue is due to phycoerythrin, a cyanobacterial

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

. It appears that, in addition to symbiotic

zooxanthella Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus '' Sym ...

, this coral harbors endocellular symbiotic cyanobacteria, possibly to help it fix

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

. However more recently, Oswold ''et al.'' (2007) showed an absence of functional phycoerythrin in ''M. cavernosa''. The species is

gonochoric In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism c ...

(colonies can be either male or female) and spawns one week after the full moon in late August. Skeletons show sex-related differences, with females having a less dense skeleton compared to males, which is presumably due to reallocating energy to egg production.

Bleaching

The distinction of bleaching in reefs of ''M. cavernosa'' from merely white-coloured corals was shown to be difficult using standard reflectance techniques. A survey in the

Bay of All Saints The Bay of All Saints ( pt, Baía de Todos os Santos), also known as All Saints' Bay and Todos os Santos Bay, is the principal bay of the Brazilian state of Bahia, to which it gave its name. It sits on the eastern coast of Brazil, surrounding p ...

concluded that this may lead to nearly two-fold overestimation of bleaching.

References

{{Taxonbar, from1=Q28043, from2=Q28040, from3=Q6022224 Scleractinia Scleractinia genera Fauna of the Caribbean Monotypic cnidarian genera