How Osmoregulation Take Place In Different Environments?

Marin
Most marine invertebrates are osmoconfermers.Among the vertebrates hag fishes are isotonic with the surroundings sea's water. Among most cartilaginous fishes maintain lower internal salt concentration than that of sea's water. Their kidneys for osmoregulation excrete salts through gills and also possess salt excreting organs such as rectal glands. These employ active transport mechanism t remove salt against osmotic gradient. Some fishes have relatively low salts in body fluids but have rendered these hypertonic to that of sea's water by retaining urea in adequate concentration. Because urea in high concentration is damaging to these fishes retain another chemical trimethyleamine oxide for protection against urea.
Fresh Water
Fresh water animals are constantly facing the osmotic flooding of body fluids and loss of salts. Fresh water protozoa, Amoeba and paramecium pump out excess water by structure, contractile vacuoles. Many fresh water animals including fishes remove excess water by producing large volume of very dilute urine. The loss of salts is compensated by reference of salt containing food and by active uptake of salts by gills and skin.
Terrestrial
The evaporative loss of water leading to dehydration is the major problem for terrestrial life. Arthropods and vertebrates have successfully adapted to terrestrial mode of life. Terrestrial animals are covered by body surface, which prevents loss of water as the waxy exoskeletons of insects and multi-layered dead, keratinized skin cells of most terrestrial vertebrates.
Terrestrial animals produce concentrated urine by possessing the kidneys that reabsorb most filtered water in the process of excretion. Terrestrial animals can tolerate dehydration and it differs in various animals. This characteristic is known as anhydrobiosis.