''Phaxas pellucidus'', the transparent razor shell, 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 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, bival ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

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 within ...

. It is found buried in the

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

in coastal waters of northwest Europe, often in great numbers.

Description

''P. pellucidus'' is a very small razor shell seldom exceeding in length. The colour is cream or dull white, sometimes with reddish markings. 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 and ...

is olive-coloured and glossy. The two elongated

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 ...

are fragile and equal in size. The dorsal side of each is straight while the ventral side is slightly curved giving a pod-like appearance. The anterior end is rounded while the posterior end is slightly truncate. There are fine sculptured lines parallel to the margins, which are themselves smooth. The ligament joining the valves is external and located close to the beaks which are very close to the anterior end.Phaxas pellucidus (Pennant, 1777)
''Marine Bivalve Shells of the British Isles''. Retrieved August 10, 2011. '' Pharus legumen'' is a somewhat similar species but it can be distinguished by its larger size and more cylindrical outline and the differences in the hinge teeth.Phaxas pellucidus (Pennant, 1777) Transparent Razor
''Conchological Society of Great Britain and Ireland''. Retrieved August 10, 2011.

Distribution

''P. pellucidus'' occurs in the northeastern

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 ...

, ranging from

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 ...

and 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 from ...

southwards to

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") , i ...

and

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

, including the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

and

English Channel The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" (Cotentinais) or ( Jèrriais), (Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kana ...

. It is found around the coasts of 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, ...

.Phaxas pellucidus (Pennant, 1777)
''Encyclopedia of Life''. Retrieved August 10, 2011.

Biology

This species is often abundant in muddy sand at depths of up to 200 metres. It is a

filter feeder Filter feeders are a sub-group of suspension feeding 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 feedin ...

and extends its siphons to the surface to circulate water through its mantle where it extract food fragments. Studies in

Liverpool Bay Liverpool Bay is a bay of the Irish Sea between northeast Wales, Cheshire, Lancashire and Merseyside to the east of the Irish Sea. The bay is a classic example of a region of freshwater influence. Liverpool Bay has historically suffered from red ...

show that where the sea bed has been disturbed by dredging and deposition of further sediment has occurred, ''P. pellucidus'' and the

polychaete Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...

worm ''

Lagis koreni ''Lagis koreni'', commonly known as the trumpet worm, is a species of marine polychaete worm found in European waters. It lives within a narrow conical tube made of grains of sand and shell fragments. Taxonomy In 1986, Holthe studied the family ...

'' often come to dominate the

community A community is a social unit (a group of living things) with commonality such as place, norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area (e.g. a country, village, tow ...

, which includes another bivalve, ''

Abra alba ''Abra alba'', or the white furrow shell, is a species of bivalve mollusc in the family Semelidae. It occurs in the northeastern Atlantic Ocean and the Mediterranean Sea, where it lives on the floor in shallow areas buried in soft sediments. Des ...

''. In the study, this particular community is believed to be associated with more than one

biotope A biotope is an area of uniform environmental conditions providing a living place for a specific assemblage of plants and animals. ''Biotope'' is almost synonymous with the term "habitat", which is more commonly used in English-speaking countrie ...

(the habitat of a community).

References

External links

* {{Taxonbar, from=Q3013254 Pharidae Molluscs of the Atlantic Ocean Molluscs described in 1777 Taxa named by Thomas Pennant