genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
octocoral
Octocorallia (also known as Alcyonaria) is a class of Anthozoa comprising around 3,000 species of water-based organisms formed of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians (sea fan ...
s 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 ...
Melithaeidae. Members of the genus are commonly known as fan corals and are found in the tropical Indo-Pacific region. The
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...
Members of the genus ''Melithaea'' are arborescent
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 ...
corals forming fan, bush or tree shapes. The axis or main skeletal "trunk" is jointed, there being nodes, flexible horny joints, separated by internodes composed of hard, calcareous material. The branches divide off at the nodes which are often swollen. The minute calcareous spicules in the flexible membrane called the
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 ...
that covers the skeleton are called
sclerite
A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...
s. The identity of these spicules is important for identification purposes and in this genus they are predominantly double discs and small disc-spindles, but also include plain spindles, capstans and small clubs. Members of this genus do not have the unicellular symbiotic algae
Zooxanthellae
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 ''S ...
in their tissues that many other corals do. Colonies vary in colour but tend to be shades of yellow, orange, red and brown.
Ecological significance
These corals are one of several genera of sea fan that can be hosts to a species of
pygmy seahorse
The pygmy seahorses comprise several species of tiny seahorse in the syngnathid family (biology), family or Syngnathidae (seahorses and pipefish). Family Syngnathidae is part of order Syngnathiformes, which contains fishes with fused jaws that su ...
, the Denise's pygmy seahorse ''(Hippocampus denise).''
Species
The World Register of Marine Species includes the following
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 ...