Every habitat in the marine environment has its own unique structure and problems that the organisms living there have to deal with. Unlike terrestrial creatures, fish (and other marine creatures) have to overcome or adapt to these problems. Most of the adaptations that fish have are aimed at maintaining the balance between their internal conditions and the external environment. The systems of fish are very sensitive and can work in a certain narrow range of conditions. For this reason, fish have to keep their internal environment in a certain balance, regardless of environmental conditions.
Osmoregulation in Fish (Regulation of Water-Salt Balance)
Osmoregulation is a biological phenomenon that ensures the maintenance of a certain, appropriate salt-water balance in the organism. Living cells need an environment that contains certain substances, including ions, dissolved in water and in certain densities. It contains the internal environment required by the cells of fish, namely body fluids, dissolved salts and organic compounds.
The amounts of these substances determine the osmotic density of body fluids. Osmotic density is expressed as milli-oz-mole/kilogram, briefly mOsm/kg.
Deviations from the normal state, such as dehydration or excess water intake, changes in body ion concentrations, can lead to physiologically dangerous situations. The organs responsible for osmoregulation in fish are mainly kidneys and gills. In addition to playing a role in removing excess water with some of the metabolic wastes, the kidneys also excrete some mineral salts or It also keeps it in the body. On the other hand, the gills, which function as the primary respiratory organ, also contain nitrogenous substances formed as a result of metabolism. It has an important role in removing some ions from the environment by throwing out most of the wastes. Also in other vertebrates As with fish, intestine and skin also play a role in osmoregulation.
