Gammarus pulex is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of amphipod

Amphipoda

Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...

 crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

 found in fresh water

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 across Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

. It is a greyish animal, growing to 21 mm (0.826771653543307 in) long.

Description

Adult males of Gammarus pulex may reach a total length of 21 millimetre (0.826771653543307 in), while females only grow to 14 mm (0.551181102362205 in). The adults have a robust appearance; they are typically greyish with markings in dark brown or green.

Distribution

G. pulex is found across Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 from eastern Siberia

Siberia

Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

 in the east to the British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

 in the west. It is absent from Norway, parts of Scotland, and Ireland, although it was introduced to Lough Neagh

Lough Neagh

Lough Neagh, sometimes Loch Neagh, is a large freshwater lake in Northern Ireland. Its name comes .-Geography:With an area of , it is the largest lake in the British Isles and ranks among the forty largest lakes of Europe. Located twenty miles to the west of Belfast, it is approximately twenty...

 in the 1950s, where it is replacing the native Gammarus duebeni. In Great Britain, G. pulex is one of only two native species of Gammarus, the other being Gammarus lacustris

Gammarus lacustris

Gammarus lacustris is an aquatic amphipod.-Description:G. lacustris is semi-transparent and lacks a webbed tail. It may be colorless, brown, reddish or bluish in color, depending on the local environment. It has seven abdominal segments, a fused cephalothorax, and two pairs of antennae. Unlike...

of Scottish loch

Loch

Loch is the Irish and Scottish Gaelic word for a lake or a sea inlet. It has been anglicised as lough, although this is pronounced the same way as loch. Some lochs could also be called a firth, fjord, estuary, strait or bay...

s.

Taxonomic history

Gammarus pulex was one of the species included in the 10th edition

10th edition of Systema Naturae

The 10th edition of Systema Naturae was a book written by Carl Linnaeus and published in two volumes in 1758 and 1759, which marks the starting point of zoological nomenclature...

 of Carl Linnaeus' Systema Naturae

Systema Naturae

The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...

, which marks the starting point for zoological nomenclature, in 1758. Linnaeus called the species Cancer pulex, the specific epithet  being Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 for "flea

Flea

Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...

". His description

Species description

A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...

 was, however, vague, and could apply to "nearly every species of amphipod". Some of Linnaeus' references refer to freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 species, while others refer to marine species. The application of the name was settled in 1970 by the redescription of the species and the selection of a neotype from a stream on the Swedish

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 island of Öland

Öland

' is the second largest Swedish island and the smallest of the traditional provinces of Sweden. Öland has an area of 1,342 km² and is located in the Baltic Sea just off the coast of Småland. The island has 25,000 inhabitants, but during Swedish Midsummer it is visited by up to 500,000 people...

.

The name Rivulogammarus has been used for a part of the genus Gammarus

Gammarus

Gammarus is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most speciose genera of crustaceans...

when it is split into smaller genera, and G. pulex has sometimes been called Rivulogammarus pulex. This name is, however, invalid under the International Code of Zoological Nomenclature

International Code of Zoological Nomenclature

The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...

, since G. pulex is the type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

of the genus Gammarus, and the genus that contains it must therefore be named Gammarus.