''Codium tomentosum'' 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 ...

of green seaweed 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 ...

Codiaceae Codiaceae is a family of green algae in the order Bryopsidales. Genera * † '' Abacella'' Maslov * '' Appeninocodium'' O.Dragastan * '' Arabicodium'' G.F.Elliott * '' Bevocastria'' E.J.Garwood * '' Botryella'' V.P.Shuysky * '' Boueina'' ...

. Its common names include velvet horn and spongeweed.

Description

The holdfast of ''C. tomentosum'' is saucer-shaped and has closely woven strands giving it a uniform appearance. The

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms ...

or frond has a

dichotomous A dichotomy is a partition of a whole (or a set) into two parts (subsets). In other words, this couple of parts must be * jointly exhaustive: everything must belong to one part or the other, and * mutually exclusive: nothing can belong simult ...

, much branched structure with thin branches, each with a circular cross section. It grows to 30 cm (12 in) in length and is spongy, with the texture of felt. It is covered with colourless hairs which are visible when it is submerged.Velvet horn - ''Codium tomentosum''

Marine Life Information Network The Marine Life Information Network (MarLIN) is an information system for marine biodiversity for Great Britain and Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic O ...

. Retrieved 2011-09-17.

Distribution and habitat

''C. tomentosum'' is native to the north east

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

from the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

southwards to the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

and Cape Verde. It has also been recorded around the coasts of Africa and in various other parts of the world.''Codium tomentosum'' Stackhouse
AlgaeBase. Retrieved 2011-09-17. The type locality is England. It is found on exposed rocks in deep rock pools on the lower shore.

Ecology

The related taxon, ''C. fragile'' subsp. ''tomentosoides'', has been spreading to various parts of the world, and a study was undertaken in 2003 in Guernsey to see whether it was displacing or even eliminating ''C. tomentosum'' from the island. It was found that, on the contrary, the native species was still thriving on the lower shore and that ''C. fragile'' subsp. ''tomentosoides'' was restricted to rock pools in the upper mid-littoral region. A similar study undertaken in 2000 on exposed shores in western

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

showed that, as compared to thirty years earlier, ''C. fragile'' subsp. ''tomentosoides'' had decreased while ''C. fragile'' subsp. ''atlanticum'' had increased. The native ''C. tomentosum'' had maintained its population size and not been displaced. The sea slug '' Elysia viridis'' (the "sap-sucking slug") feeds on ''C. tomentosum'' and ''C. fragile'' and has a symbiotic relationship with them. When the fluids from the algae are ingested, the chloroplasts remain intact and photosynthetically active in the digestive

diverticula In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...

of the slug for some days. They continue to synthesize sugars which the slug then metabolises. The activity of the chloroplasts degenerates over time and they need to be constantly replaced by further consumption of ''Codium'' spp.Taylor, D. L. (1968)
"Chloroplasts as symbiotic organelles in the digestive gland of ''Elysia viridis'' (Gastropoda: opisthobranchia)"
''Journal of the Marine Biological Association of the United Kingdom'', 48: 1-15. Retrieved 2011-09-17.The biology of chloroplast acquisition by ''Elysia viridis''
Retrieved 2011-09-22.

Research

A lectin named tomentine has been isolated by

affinity chromatography Affinity chromatography is a method of separating a biomolecule from a mixture, based on a highly specific macromolecular binding interaction between the biomolecule and another substance. The specific type of binding interaction depends on the ...

from ''C. tomentosum''. It shows N-acetylglucosamine-specific activity and has been found to be rich in

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...

, threonine and

valine Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deprotona ...

References

External links

* {{Taxonbar, from=Q5140305 tomentosum Marine biota of Africa Marine biota of Europe Plants described in 1797 Taxa named by John Stackhouse