In contrast to the situation in FW where all animals are osmoregulators, multiple strategies are employed for the control of salt and water balance in SW organisms. All teleost fish regulate extracellular ionic concentrations much below that
of SW and are thus both osmoregulators and ionoregulators. All elasmobranch fish maintain osmotic pressure of extracellular fluids similar to the surroundings but maintain ion concentrations at approximately 50%of SW(the discrepancy made up by organic osmolytes) and are thus characterized as osmoconformer