Why is it that salt water animals do not survive in fresh environment?

Salt water animals, also known as marine organisms, have evolved and adapted to the high salinity levels found in ocean water. When placed in a fresh water environment, their bodies experience a sudden change in osmotic pressure.

Osmotic pressure refers to the tendency of water molecules to move from an area of lower solute concentration to an area of higher solute concentration. In this case, the fresh water has a lower concentration of dissolved salts compared to the salt water animals' body fluids. As a result, water from within the animal's body moves out into the surrounding fresh water in an attempt to equalize the concentrations.

This loss of water from the animal's body leads to dehydration, disrupting various physiological processes. The cells shrink and lose their normal function, ultimately leading to organ failure and eventually death. The delicate balance of water and salt concentrations in the body, known as homeostasis, is disrupted, making it challenging for the animal to survive.

Additionally, fresh water poses other physiological challenges for salt water animals. For instance, the lower salinity levels can disrupt their ion balance, affecting the function of vital enzymes and proteins. The reduced buoyancy in fresh water can also hinder their ability to move and hunt for food efficiently.

Therefore, while some salt water animals may exhibit some tolerance to low salinity conditions for a short period, their long-term survival in a fresh water environment is highly unlikely due to the drastic differences in osmotic pressure and the disruption of their physiological processes.