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

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two sh ...

, a marine

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

mollusc 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 ...

Pharidae Pharidae is a taxonomic family of saltwater clams, marine bivalve molluscs in the order Adapedonta. This family of clams is related to the razor shells, a family which is considered to include Pharidae by some authorities. Genera Genera wit ...

. 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 fitting ...

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 a ...

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'' and ''

Ensis arcuatus ''Ensis'' is a genus of medium-sized edible saltwater clams, littoral bivalve molluscs in the family Pharidae. ''Ensis'', or razor clams, are known in much of Scotland as spoots, for the spouts of water they eject while burrowing into the ...

'' 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.Conchological Society of Great Britain and Ireland
/ref>

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 Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and fr ...

and

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

to the Atlantic coast of

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' ( Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...

and

Portugal Portugal, officially the Portuguese Republic, In recognized minority languages of Portugal: :* mwl, República Pertuesa is a country located on the Iberian Peninsula, in Southwestern Europe, and whose territory also includes the Macaronesian ...

. It is common around the coasts of Britain.

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-illuminated ...

and the low

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

. 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 A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in a ...

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 (; plural larvae ) 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. Th ...

e are

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

and form part of the

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. 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 (locomotion), the surface over which an organism lo ...

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 ...

'' and '' Chamelea gallina''.Elements of Marine Ecology
/ref>

References

External links

* {{Taxonbar, from=Q602527 Pharidae Molluscs described in 1758 Taxa named by Carl Linnaeus