Homeostatic responses of crustaceans to salinity changes

The wide distribution of crustaceans from freshwater through brackish into marine waters and from salt marshes to terrestrial zones shows the exceptional capacities of this animal group to cope with salinity changes. Osmoregulation is the main physiological mechanism that maintains the hydromineral homeostasis of these animals. The difference of osmoregulation capacities between an osmoconformer and an osmoregulator species is mainly explained by anisosmotic extracellular regulation (AER) and/or isosmotic intracellular regulation (IIR). This review will also discuss the particular acquisition of specific osmoregulation capacities in crustaceans from the first embryonic stages to the adult. Several findings revealed that gills and antennal glands are the primordial hydromineral regulation tissues, and they present the same structure and function in all crustaceans, except in shrimps. These tissues contain ionocytes that harbor membrane pumps implicated in ion regulation. Na+/K+-ATPase, the major of these membrane proteins, acts upon rapid ionic changes, usually in cooperation with several other membrane pumps. Also some proteins, belonging to the detoxification and antioxidant systems, seem implicated in the regulation mechanisms after salinity change. This review will resume and discuss the current knowledge on salinity regulation in this large and important animal group.