Tellina tenuis
Encyclopedia
Tellina tenuis, the thin tellin, is a species of marine bivalve
mollusc
in the family
Tellinidae
. It is found off the coasts of north west Europe and in the Mediterranean Sea where it lives buried in sandy sediments.
Bivalves are molluscs with a body compressed between two usually similar shell valves
joined by an elastic ligament. There are teeth at the edge of the shell and the animal has a muscular foot, gill
s, siphons, mouth and gut and is surrounded by a mantle
inside the shell.
is glossy and the colour varies through shades of pink, yellow and brown, often in bands. There is a sculpture of fine concentric lines which is grouped into growth stages and which may be emphasized by bands of colour. The inner sides of the valves are similarly coloured but paler. The mantle
is fringed with tentacle
s and is creamy-white.
and in the Mediterranean Sea
and the Baltic Sea
. It is found from the middle shore level to a depth of about seven metres. It is widely distributed and common around the coasts of the British Isles.
. The mollusc usually lies on its left side when feeding. When the tide is out it descends to a depth of about ten centimetres but ascends to nearer the sediment surface when feeding. At the low tide level it may be the most abundant macro-organism in the benthos
and may reach a density of 3000 individuals per square metre.
Individual molluscs are either male or female and gamete
s are liberated into the water table
during the summer. The larva
e are free swimming and form part of the zooplankton
for a period. The lifespan is up to 5 years.
is found over the same distribution range but the two are not usually in competition as T fabula occurs from low water level to a depth of about forty metres. Because of its greater exposure at low tides, T tenuis is more susceptible to harm in cold winter weather.
Young flatfish
sometimes feed on the tips of the protruding siphons. The damaged siphons are able to regenerate.
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
mollusc
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Tellinidae
Tellinidae
Tellinidae is a family of marine bivalve molluscs of the order Veneroida. They live under soft sediments in shallow seas.-Characteristics:Tellinids have rounded or oval, elongated shells, much flattened. The two valves are connected by a large external ligament. The two separate siphons are...
. It is found off the coasts of north west Europe and in the Mediterranean Sea where it lives buried in sandy sediments.
Bivalves are molluscs with a body compressed between two usually similar shell valves
Bivalve shell
A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk. In life, the shell of this class of mollusks is composed of two parts, two valves which are hinged together...
joined by an elastic ligament. There are teeth at the edge of the shell and the animal has a muscular foot, gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s, siphons, mouth and gut and is surrounded by a mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
inside the shell.
Description
The shell of T. tenuis is brittle and flattened and grows to up to nineteen centimetres in length. The outline is oval but the valves are asymmetric with the hinge slightly off centre and the beaks slightly behind the midline. The posterior of the valves is attenuated slightly and the right valve is slightly larger than the left. An olive green ligament joins the two valves. The periostracumPeriostracum
The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...
is glossy and the colour varies through shades of pink, yellow and brown, often in bands. There is a sculpture of fine concentric lines which is grouped into growth stages and which may be emphasized by bands of colour. The inner sides of the valves are similarly coloured but paler. The mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
is fringed with tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s and is creamy-white.
Distribution
T. tenuis occurs off the coasts of north west Europe and MoroccoMorocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
and in the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
and the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
. It is found from the middle shore level to a depth of about seven metres. It is widely distributed and common around the coasts of the British Isles.
Biology
T. tenuis burrows in clean sand and has a large foot and two long siphons which it extends to the surface of the sediment. Water and food particles are drawn down to the mollusc through one siphon while water is expelled through the other. It is both a deposit and a filter feederFilter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
. The mollusc usually lies on its left side when feeding. When the tide is out it descends to a depth of about ten centimetres but ascends to nearer the sediment surface when feeding. At the low tide level it may be the most abundant macro-organism in the benthos
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
and may reach a density of 3000 individuals per square metre.
Individual molluscs are either male or female and gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s are liberated into the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
during the summer. The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e are free swimming and form part of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
for a period. The lifespan is up to 5 years.
Ecology
The closely related species, Tellina fabulaTellina fabula
Tellina fabula is a species of marine bivalve mollusc in the family Tellinidae. It is found off the coasts of north west Europe where it lives buried in sandy sediments....
is found over the same distribution range but the two are not usually in competition as T fabula occurs from low water level to a depth of about forty metres. Because of its greater exposure at low tides, T tenuis is more susceptible to harm in cold winter weather.
Young flatfish
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
sometimes feed on the tips of the protruding siphons. The damaged siphons are able to regenerate.