Osmosis:
* Saltwater fish are hypertonic: Their cells have a higher concentration of solutes (salts) compared to the surrounding seawater. This means water tends to move out of the fish's cells to balance the concentration gradient.
* Freshwater is hypotonic: Freshwater has a much lower concentration of solutes than the fish's cells. This means water will rush into the fish's cells to try and dilute the internal concentration.
Consequences:
* Cell swelling: The influx of water into the fish's cells causes them to swell, potentially leading to cell lysis (bursting).
* Electrolyte imbalance: The movement of water also disrupts the balance of electrolytes (salts) within the fish's body.
* Organ damage: The swelling and electrolyte imbalance can damage organs, leading to various health problems.
* Death: If the fish is not returned to saltwater or given appropriate treatment, it will eventually die from the osmotic shock.
Adaptations:
* Saltwater fish are adapted to their environment: They have evolved specialized mechanisms to maintain their internal salt balance and prevent excessive water loss. These include:
* Gills: Saltwater fish use their gills to actively pump out excess salt and absorb water.
* Kidneys: Their kidneys are adapted to produce concentrated urine, minimizing water loss.
* Drinking: They drink saltwater to replenish their water supply.
In summary: Putting a saltwater fish in freshwater is a drastic change that can lead to significant cellular damage and even death. It's crucial to remember that saltwater fish are highly adapted to their salty environment, and any change in salinity can have severe consequences.