Gammarus chevreuxi is a species of crustacean in the family Gammaridae.

The organism is very similar to Gammarus locusta, but there are certain constant characteristic which set it apart, for example, the antennae, the fourth side-plates and the third uropods.

[2] The eyes of G. chevreuxi are made up of black facets separated by white pigment.

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.

[3] Correspondingly the white pigment separating the facets maybe missing by another mutation.