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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of colonial soft

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Plexauridae Plexauridae is a Family (biology), family of marine Colony (biology), colonial Octocorallia, octocorals in the phylum Cnidaria. Members of this family are found in shallow tropical and subtropical seas. Many species contain Symbiosis, symbiotic P ...

. 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 naturalist from Nice. Risso was born in the city of Nice in the Duchy of Savoy, and studied under Giovanni Battista Balbis. He published ' (1810), ' (1826) an ...

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 Gorgonin is a flexible scleroprotein which provides structural strength to gorgonian corals, a subset of the order Alcyonacea. Gorgonian corals have supporting skeletal axes made of gorgonin and/or calcite. Gorgonin makes up the joints of bambo ...

, 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 ...

, 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 main ...

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 An ecosystem engineer is any species that creates, significantly modifies, maintains or destroys a habitat. These organisms can have a large impact on species richness and landscape-level heterogeneity of an area. As a result, ecosystem engine ...

, 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 Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

, the polyps extending their tentacles to catch food particles floating past. Its diet includes

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

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

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, which are not related to cnidarians at all. Some groups of Nemerteans also produce larva ...

larvae into the water column. The larvae are photophobic and soon settle on the seabed. Once there, they develop into polyps and start secreting

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