6.4

6.4 Osmoregulation: Sea water has a similar water potential to the body fluids of most marine organisms, and therefore many species do not need to regulate their water content. Other species are osmoregulators and control the water content of their bodies. Most marine organisms can survive within only a small range of salinity, and are termed stenohaline. Euryhaline species can live in a range of salinities. Salmon are an example of a euryhaline osmoregulator, spending part of their life cycle in the sea and part in fresh water.