Osmoregulators have internal solute concentrations compared to their external environment.

Osmoregulation is the active regulation of water and electrolytes in an organism to perform biochemical reactions and maintain homeostasis. Osmoregulators organisms actively control salt concentrations irrespective of the salt concentrations in the environment. Since they actively control the salt concentrations, they spend a high amount of energy.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.