Organisms are either osmoregulators or osmoconformers.

• Osmoregulators are organisms which have specialised mechanisms for the purpose of regulating both internal water and solute concentrations, irrespective changes in concentrations in the external environment
  

• Osmoconformers are organisms which have their internal solute concentration alter alongside changes with the concentration of solutes in the external environment; they rely on the external environment for osmoregulation

Adaptations for osmoregulation (osmoregulators)