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The brine shrimp Artemia is an inhabitant of hypersaline environments and has been used to study primary reproductive traits and mating behaviour together with the degrees of divergence among populations. Intrapopulation experimental crosses and cross-fertility tests were evaluated in four populations from coastal and inland environments of South India, and in a reference sample of A. franciscana (San Francisco Bay -SFB, U.S.A). Crosses were fertile with the production of live nauplii and cysts. Significant variations were observed among the populations studied in fecundity (e.g. total offspring, brood size). A reproductive switch from ovoviviparity to oviparity was observed, especially in crosses between inland populations with the reference strain. Differences between the South Indian samples and SFB were significant- for the total number of nauplii, percentage of encysted brood and broods per female. A peculiar pattern of male-male mating was observed, wherein the ratio of males was higher than females. About 70% of the orientation movements of the males were directed towards other males. [ABSTRACT FROM AUTHOR]