Fish, specifically those living in saltwater environments, drink masses of seawater.
Why Do Fish Drink Seawater?
Marine fish face a constant challenge because their internal body fluids are less salty than the surrounding seawater. This causes them to lose water through their skin and gills via a process called osmosis.
Osmosis Explained
Osmosis is the movement of water from an area of higher concentration (less salty) to an area of lower concentration (more salty) across a semi-permeable membrane, such as a fish's skin or gills.
The Dehydration Problem
Because of osmosis, marine fish are constantly losing water to their environment. To avoid dehydration, they compensate by drinking a large amount of seawater.
How Marine Fish Process Seawater
- Drinking Seawater: Marine fish actively drink seawater to replenish the water they lose.
- Salt Excretion: They excrete excess salt through their gills and produce a small amount of highly concentrated urine. This helps them maintain the correct balance of water and salt in their bodies.
| Process | Description |
|---|---|
| Osmosis | The movement of water from an area of low salt concentration to an area of high salt concentration across a semi-permeable membrane. |
| Dehydration | The loss of water from a fish's body due to osmosis. |
| Water Intake | Marine fish drink large amounts of seawater to replace lost water. |
| Salt Balance | Marine fish excrete excess salt through their gills and produce concentrated urine to maintain the correct balance of water and salt. |
It is important to note that freshwater fish do not drink water in the same way as marine fish. They actually absorb water through their skin and gills due to the opposite osmotic pressure. This is another whole process in itself.
