''Gammarus chevreuxi'' is a species of

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

in the family

Gammaridae Gammaridae is a family of amphipods. In North America they are included among the folk taxonomic category of " scuds", and otherwise gammarids is usually used as a common name. They have a wide distribution, centered on Eurasia, and are eury ...

. It was first described by

Elsie Wilkins Sexton Elsie Wilkins Sexton (née Wing, 27 April 1868 – 18 February 1959) was an English zoologist and biological illustrator. Biography Early life and education Sexton was born Alice Wilkins Wing at Truro, Cornwall on 27 April 1868. She stud ...

in 1913. The organism is very similar to ''

Gammarus locusta ''Gammarus locusta'' is a species in the family Gammaridae ("scuds"), in the order Amphipoda ("amphipods").bugguide.net

'', but there are certain constant characteristic which set it apart, for example, the antennae, the fourth side-plates and the third

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

s. It is found in various places in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

, such as the

Severn Estuary The Severn Estuary ( cy, Aber Hafren) is the estuary of the River Severn, flowing into the Bristol Channel between South West England and South Wales. Its high tidal range, approximately , means that it has been at the centre of discussions in t ...

, and in

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 ...

Eyes and heredity

The eyes of ''G. chevreuxi'' are made up of black facets separated by white pigment. A mutation causes red facets. The recessive nature of the gene means that red-eyed populations breed true, being homozygous, while heterozygous black eyed populations may have either red-eyed or black-eyed offspring, in an illustration of

Mendel's law of segregation Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularize ...

. Correspondingly the white pigment separating the facets maybe missing by another mutation. This characteristic is inherited independently of the colour of the facets, illustrating Mendel's law of independent assortment.

References

chevreuxi Crustaceans of the Atlantic Ocean Crustaceans described in 1913 {{amphipod-stub