tArtemia (Anostraca) is among the most primitive and ancient groups of crustaceans. Artemia spp. playa dominant role in the ecosystems of hypersaline waters, and often they are the only animals in theseextreme biotopes. Most ethological studies on Artemia have been conducted on nauplii and metanauplii.We made ethological observations on Artemia under laboratory conditions and in the natural watersof Crimea (Russia), where we studied growth and ontogenetic changes of swimming behavior. Growthoccurred during the first 50 days up to a size of 9.5–10.5 mm, after which time the size did not increase(some females lived up to 6.5 months). A strong positive relation was found between maximal speedand individual length, which varied between 0.4 and 10.5 mm; it may be approximated by the powerequation: Vmax= 1.205·K0.820, where Vmaxis the maximal speed of Artemia (in mm s−1) of the length K(in mm). There is no similar relation between average speed and length of Artemia. The average speedof adults was 40–60% lower in environments with microalgae compared to media without food. Theduration of the “riding position” for mating pairs of Artemia urmiana in our experiments varied from 10to 27 days. In lakes we observed different Artemia aggregations varying in size and form. We concludethat the swimming behavior of Artemia is quite complex and diverse, and develops during ontogeny.© 2014 Published by Elsevier GmbH.