''Paramuricea clavata'', the violescent sea-whip, is a

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 ...

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 ...

soft

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...

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 ...

Plexauridae Plexauridae is a family of marine colonial octocorals in the phylum Cnidaria. Members of this family are found in shallow tropical and subtropical seas. Many species contain symbiotic photosynthetic protists called zooxanthellae. Characteristi ...

. It is found in shallow seas of the north-eastern Atlantic Ocean and the north-western Mediterranean Sea as well as Ionian Sea. This species was first described by the French naturalist

Antoine Risso Giuseppe Antonio Risso (8 April 1777 – 25 August 1845), called Antoine Risso, was a Niçard and natural history, naturalist. Risso was born in the city of Nice in the Duchy of Savoy, and studied under Giovanni Battista Balbis. He published ' (1 ...

in 1826.

Description

''P. clavata'' has a branching structure forming a fan-shaped colony in a single plane. The stem and branches are stiffened by gorgonin, a complex protein that produces a horny skeleton. The

coenenchyme Coenenchyme is the common tissue that surrounds and links the polyps in octocorals. It consists of mesoglea penetrated by tubes (''solenia'') and canals of the gastrodermis and contains sclerites, microscopic mineralised spicules of silica or of ca ...

, a thin living layer of cells, covers the skeleton and the polyps protrude from this, each with eight feeding

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work ma ...

s surrounding a central mouth. The polyps are up to high and the whole colony up to one m (3 ft) high and 1 m across. The colour is usually red, but may be partly yellow.

Distribution and habitat

The violescent sea-whip is native to the coasts of Spain and Portugal in the eastern Atlantic Ocean, and to the western Mediterranean Sea. It grows on reefs with its base buried in the sediment at depths between , but usually between . It is considered to be an ecosystem engineer, as its presence alters the flow of water, changes sedimentation rates, and alters the distribution of nutrients, thus affecting many organisms in its vicinity.

Biology

''P. clavata'' is a filter feeder, the polyps extending their tentacles to catch food particles floating past. Its diet includes copepods, diatoms, dinoflagellates,

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...

s, and organic carbon particles in suspension. Each colony is either male or female. Sperm is liberated into the sea by the male colonies and fertilisation occurs on the surface of the female colonies. The embryos are brooded there before being released as

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 ...

larvae into the water column. The larvae are

photophobic Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence o ...

and soon settle on the seabed. Once there, they develop into polyps and start secreting gorgonin to form the skeleton. Further growth of the colony is by

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is kno ...

of new polyps. Some new colonies may be formed from fragments that become detached from existing colonies. ''P. clavata'' is a slow-growing species and colonies probably live for well over 50 years.

References

External links

* {{Taxonbar, from=Q146668 Plexauridae Cnidarians of the Atlantic Ocean Fauna of the Mediterranean Sea Animals described in 1826 Taxa named by Antoine Risso