Osmoregulation in Aqueous Environments
You are aware that the aqueous environments are of two types:
i) Freshwater and
ii) Seawater.
The osmotic concentration of these environments ranges from several milliosmoles per litre in freshwater lakes to about 1000 milliosmoles per litre in ordinary seawater. It is even more in landlocked saltseas. The whole body and the respiratory surface of the aquatic animals is immersed in these osmotically extreme environments. The animals which can tolerate a wide range of salinities are called euryhaline and those which tolerate only a narrow osmotic range are termed stenohaline.