''Ensis ensis'', or the sword razor, is a razor

clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

, a marine

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

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 ...

Pharidae Pharidae is a Taxonomy (biology), taxonomic family (biology), family of saltwater clams, marine (ocean), marine bivalve molluscs in the order Adapedonta. This family of clams is related to the Solenidae, razor shells, a family which is considered ...

. It lives buried in the sand and is found off the coasts of northwest Europe.

Description

The two

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, ...

that make up the shell of ''Ensis ensis'' are parallel-sided, narrow and curved. The adult shell can be up to ten centimetres in length. The valves are thin and rather brittle. The edges are parallel, tapering slightly towards the posterior and are off white with transverse bands of brown. The shell is sculpted with fine co-marginal lines and the annual growth lines can be seen. The inner side of the shell is white with a purplish sheen. The

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods an ...

is olive green and the foot is reddish. Two identifying features are that the posterior adductor muscle is positioned some one and a half times its own length from the pallial sinus, and that the muscle that retracts the foot is posterior to the insertion point of the ligature. ''

Ensis siliqua The pod razor (''Ensis siliqua'') is a coastal bivalve of European waters. It is edible and has been fished commercially, especially in Portugal, Spain, Ireland and Scotland. ''Ensis siliqua'' is also known as the razor fish, razor clam or giant ...

'' and '' Ensis arcuatus'' are two other rather similar species that can be found living in the same localities, but the shells of both of them are less curved than this species.

Right and left valve of the same specimen: File:Ensis ensis 01.jpg, Right valve File:Ensis ensis 02.jpg, Left valve

Distribution

''E. ensis'' occurs off the coasts of northwest Europe, from the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

and

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

to the Atlantic coast of

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

and

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

. It is common around the coasts of

Great Britain Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...

and

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

Biology

''Ensis ensis'' burrows into clean or silty sand on the seabed in the

neritic zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminate ...

and the low

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

. When covered with water this bivalve remains close to the surface but when disturbed or when the substrate is exposed it descends to half a metre below the surface. It can tunnel with great rapidity.Fish, J.D. and Fish, S. (1996) A student’s guide to the seashore. Second Edition. Cambridge University Press, Cambridge. It has two short siphons that normally extend up to the surface of the sand. It draws in water through one siphon and expels it through the other. By this means it both respires and extracts food particles from the water at the same time. At low tide, a keyhole-shaped depression in the sand is often the only visible sign that the bivalve is present. ''Ensis ensis'' becomes mature at about three years old and may live for ten. Reproduction takes place in the spring and the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e are

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

and form part of the

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

. After about a month they settle out and burrow into the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

Ecology

''Ensis ensis'' is often found living in association with other burrowing animals including the sea potato, '' Echinocardium cordatum'', and the bivalve molluscs ''

Tellina fabula ''Fabulina fabula'', the bean-like tellin, is a species of marine bivalve mollusc in the family Tellinidae. It is found off the coasts of northwest Europe, where it lives buried in sandy sediments. Bivalves are molluscs with a body compressed be ...

'' and ''

Chamelea gallina ''Chamelea gallina'' is a species of small saltwater clam, a marine Bivalvia, bivalve in the Family (biology), family Veneridae, the venus clams. Taxonomy Carl Linnaeus originally described ''Venus gallina'' from the Mediterranean Sea in 1758. ...

''.Elements of Marine Ecology
/ref>

References

External links

* {{Taxonbar, from=Q602527 Pharidae Bivalves of Europe Molluscs of the Atlantic Ocean Molluscs described in 1758 Taxa named by Carl Linnaeus