Science, technology, society, environment (STSE) applications
Osmosis: Understanding other organisms
Aquatic organisms must also use osmosis to maintain their internal environment in relation to their external environment.
The Atlantic salmon (Salmo salar) lives in fresh water in the first 2-3 years of its life in rivers and lakes. Here, the solute concentration is about 0.1%, less than the concentration within its body, about 1.0%. This gradient means the organism takes in water into the body, and therefore homeostatic mechanisms must expel the water out. At maturation, the salmon swims for the Atlantic Ocean, where the concentration of solute is about 3.5%. In this saltwater environment, the solute concentration inside the salmon's body is less than outside, and water is lost from the body. As a result, the salmon must replenish its water stores. |