The internal osmotic pressure varies only slightly with external conditions. In dilute sea water, Artemia is hypertonic to its medium and behaves like a brackish water organism. At higher concentrations, Artemia is an excellent hyporegulator which in concentrated brine still maintains an osmotic pressure of the body fluid of not much more than one-tenth of the medium. The brine shrimp maintains its low osmotic concentration, not by being exquisitely impermeable to water and ions, but by active regulation.
Ionic regulation appears to be maintained by the absorption or excretion of salts through the gills.
The purpose of this experiment is to study the osmotic and ionic tolerance of this unusual creature under controlled laboratory conditions. Label them with concentration and lab group. Label the tray to indicate the group number. When counting the animals, discard dead animals in the sink. When you are finished with the experiment, flush the solutions and animals down the sink and rinse the containers in tap water.