Osmosis Explained: What Happens When Freshwater Meets Saltwater?

When a fresh water cell is placed in salt water, it undergoes a process called osmosis. Osmosis is the movement of water molecules from an area of high water concentration to an area of low water concentration through a semipermeable membrane.

In this case, the fresh water cell is surrounded by a semipermeable cell membrane, which allows water molecules to pass through but blocks the passage of larger molecules such as proteins and carbohydrates. Because the salt water concentration is higher than the fresh water cell concentration, water molecules will move out of the cell and into the salt water by osmosis.

As a result, the fresh water cell will shrink and become less turgid. In severe cases, the cell may even burst due to the osmotic pressure. This process of dehydration can damage cell structures and ultimately lead to the death of the cell.

To prevent this from happening, fresh water organisms have evolved various adaptations to maintain their internal water balance. These adaptations may include the ability to accumulate salts and other solutes to match the external salt concentration, or the presence of specialized structures that reduce water loss.