The green crab (Carcinus maenas) is an example of a euryhaline invertebrate that can live in salt and brackish water.
Euryhaline organisms are commonly found in habitats such as estuaries and tide pools where the salinity changes regularly.
However, some organisms are euryhaline because their life cycle involves migration between freshwater and marine environments, as is the case with salmon and eels.
The osmotic pressure in the body is homeostatically regulated in such a manner that it keeps the organism's fluids from becoming too diluted or too concentrated.
Osmoregulators tightly regulate their body osmolarity, which always stays constant, and are more common in the animal kingdom.
Salmon has been observed to inhabit two utterly disparate environments — marine and fresh water — and it is inherent to adapt to both by bringing in behavioral and physiological modifications.
However, the osmotic pressure between their internal fluids and external environment still causes water to diffuse into their bodies, and they must produce large quantities of dilute urine (at 10 times the rate of marine individuals) to compensate.