''Gammarus pulex'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

amphipod Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

found in

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ...

across much of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

. It is a greyish animal, growing to long.

Description

Adult males of ''Gammarus pulex'' may reach a total length of , while females only grow to . The adults have a robust appearance; they are typically greyish with markings in dark brown or green. Individuals of the genus '' Dendrocometes'' are known to be parasites which reside on the gills of ''G. pulex''.

Distribution

''Gammarus pulex'' is found across most of

from the

Volga The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...

drainage in the east to the

British Isles The British Isles are an archipelago in the Atlantic Ocean, 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 Hebrides, Inner and Outer Hebr ...

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

Lough Neagh Lough Neagh ( ; ) is a freshwater lake in Northern Ireland and is the largest lake on the island of Ireland and in the British Isles. It has a surface area of and is about long and wide. According to Northern Ireland Water, it supplies 4 ...

in the 1950s, where it is replacing the native '' Gammarus duebeni''.

Taxonomic history

''Gammarus pulex'' was one of the species included in the

10th edition 1 (one, unit, unity) is a number, numeral, and glyph. It is the first and smallest positive integer of the infinite sequence of natural numbers. This fundamental property has led to its unique uses in other fields, ranging from science to sp ...

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

' ''

Systema Naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...

'', which marks the starting point for

zoological nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...

, in 1758. Linnaeus called the species ''Cancer pulex'', the

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

' being

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for "

flea Flea, the common name for the order (biology), order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by hematophagy, ingesting the blood of their hosts. Adult f ...

". His

description Description is any type of communication that aims to make vivid a place, object, person, group, or other physical entity. It is one of four rhetorical modes (also known as ''modes of discourse''), along with exposition, argumentation, and narr ...

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

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

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 In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...

from a stream on the

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

island of

Öland Öland (, ; ; sometimes written ''Oland'' internationally) is the second-largest Swedish island and the smallest of the traditional provinces of Sweden. Öland has an area of and is located in the Baltic Sea just off the coast of Småland. ...

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

Gammarus ''Gammarus'' is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most species-rich genera of crustaceans. Different species have different optimal conditions, particularly ...

'' 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 The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...

, since ''G. pulex'' is the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

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

Parasites

''Gammarus pulex'' are known to be infected by at least three different species of acantocephalan parasites, ''

Pomphorhynchus laevis ''Pomphorhynchus laevis'' is an endo-parasitic acanthocephalan worm, with a complex life cycle, that can modify the behaviour of its intermediate host, the freshwater amphipod ''Gammarus pulex''. ''P. laevis'' does not contain a digestive tract ...

'', '' P. minutus'', and '' P. tereticollis''.

References

{{Authority control pulex Freshwater crustaceans of Europe Freshwater crustaceans of Asia Crustaceans described in 1758 Taxa named by Carl Linnaeus