The worldwide distribution of brine shrimp in a variety of isolated habitats, each one
characterised by its own ecological conditions, has furthermore resulted in the existence of
numerous geographical strains, or genetically different populations within the same sibling
species; in particular the parthenogenetic Artemia with its di-, tri-, tetra- and pentaploid
populations display a wide genotypic variation. Among these strains a high degree of genetic
variability as well as a unique diversity in various quantitative characteristics have been
observed. Some of these characteristics (i.e. the nutritional value of freshly-hatched nauplii)
are phenotypical, and change from year to year or season to season. Others, however (i.e.
cyst diameter, growth rate, resistance to high temperature) are strain specific and remain
relatively constant, (i.e. they have become genotypical as a result of long-term adaptations of
the strain to the local conditions; see chapter 4.1.2.4