Corophium is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of the amphipod family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Corophiidae

Corophiidae

Corophiidae is a family of amphipods, containing the following genera:*Americorophium Bousfield & Hoover, 1997*Anonychocheirus Moore & Myers, 1983*Apocorophium Bousfield & Hoover, 1997*Bathyphotis Stephensen, 1944*Cheirimedeia J. L...

. Formerly a much larger genus, many species have been transferred to segregate genera

Segregate (taxonomy)

In taxonomy, a segregate, or a segregate taxon is created when a taxon is split off, from another taxon. This other taxon will be better known, usually bigger, and will continue to exist, even after the segregate taxon has been split off...

 such as Monocorophium

Monocorophium

Monocorophium is a genus of amphipod crustaceans.-Species:The genus Monocorophium comprises the following species:*Monocorophium acherusicum *Monocorophium californianum...

and Crassicorophium

Crassicorophium

Crassicorophium is a genus of amphipod crustaceans, comprising three species:*Crassicorophium bonellii *Crassicorophium clarencense *Crassicorophium crassicorne...

.

Species

Corophium contains 12 species, after the genus was divided into a number of new genera in 1997:

• Corophium arenarium Crawford, 1937
• Corophium bicaudatus Linnaeus, 1761
• Corophium colo Lowry, 2004
• Corophium denticulatum Ren, 1995
• Corophium grossipes Linnaeus, 1767
• Corophium laevicorne Sowinsky, 1880
• Corophium linearis Pennant, 1777
• Corophium longicornis J. C. Fabricius, 1779
• Corophium multisetosum Stock, 1952
• Corophium orientale Schellenberg, 1928
• Corophium urdaibaiense Marquiegui & Perez, 2006
• Corophium volutator
  Corophium volutator
  Corophium volutator, one of several organisms called mud shrimp, is a small amphipod of the family Corophiidae.It inhabits the upper layers of sand on the coasts of the Netherlands, Germany, the United Kingdom and France, as well as in the Bay of Fundy on the coasts of Nova Scotia and New...
  
  (Pallas, 1766)

Corophium arenarium

C. arenarium may reach 7 mm long and looks very similar to C. volutator

Corophium volutator

Corophium volutator, one of several organisms called mud shrimp, is a small amphipod of the family Corophiidae.It inhabits the upper layers of sand on the coasts of the Netherlands, Germany, the United Kingdom and France, as well as in the Bay of Fundy on the coasts of Nova Scotia and New...

. It burrows in bottom sediments, between 10 and 60 metres deep. C. arenarium occurs on the coasts of France and the North Sea.

Corophium multisetosum

C. multisetosum may grow to 9 mm and builds mud burrows in clay or sand in fresh or weakly brackish habitats. It occurs on the coasts of the Netherlands, France, Germany, Poland and the British Isles.

Corophium volutator

C. volutator inhabits the upper layers of sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

 on the coasts of the Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 and France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, as well as in the Bay of Fundy

Bay of Fundy

The Bay of Fundy is a bay on the Atlantic coast of North America, on the northeast end of the Gulf of Maine between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine...

, New Brunswick

New Brunswick

New Brunswick is one of Canada's three Maritime provinces and is the only province in the federation that is constitutionally bilingual . The provincial capital is Fredericton and Saint John is the most populous city. Greater Moncton is the largest Census Metropolitan Area...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. They grow to 10 mm, and can occur in huge quantities: up to 40,000 per square metre have been observed.