Salmon exhibit osmoregulatory adaptations to thrive in varying salinities, primarily through the actions of Na+-Cl- ATPase. In marine environments, this enzyme expels sodium and chloride ions from the salmon's blood into saltwater, maintaining osmotic balance. Conversely, in freshwater, the same mechanism allows salmon to absorb these ions from the surrounding water, ensuring proper bodily function. The physiological changes allow salmon to efficiently navigate their life cycle between the ocean and freshwater rivers, which presents significant evolutionary advantages.