Changes

=====Saltwater=====

=====Saltwater=====

The environment is hypotonic compared to the body of the fish therefore water is lost across their gills so they drink sea water to replace this which results in a large intake of salt (activates Angiotensin 2).  They excrete both ammonia and NaCl across their gills and further NaCl across their skin.  Their kidneys have small or absent glomeruli and their main function is the elimination of excess divalent ions e.g. Mg²⁺

The environment is hypertonic compared to the body of the fish therefore water is lost across their gills so they drink sea water to replace this which results in a large intake of salt (activates Angiotensin 2).  They excrete both ammonia and NaCl across their gills and further NaCl across their skin.  Their kidneys have small or absent glomeruli and their main function is the elimination of excess divalent ions e.g. Mg²⁺

==Amphibian==

==Amphibian==