The regulation of salt (NaCl) & water (H²O) content of the body is one the most essential functions of living organisms. Any environment that isn't isotonic with blood plasma presents a water balance problem, and any environmental fluid not possessing the exact same mixture & concentrations of salts as the tissue fluids introduce the need for salt-regulatory mechanisms. Essentially all organisms possess osmoregulation problems to a certain degree. The problem may be solved by some combination of water excretory mechanisms for active reabsorption or excretion of salts. This process can become more complex by the need of the organism to excrete its metabolic wastes, a process that often involves wasting water.
             The importance of the ability of amphibians to osmoregulate in air cannot be minimized because they were the first vertebrate group to exploit the terrestrial environment. More recent vertebrate evolutionary lineages, the reptiles, birds and mammals, have developed adaptations such as more impervious integuments, more efficient kidneys, and the amniotic egg which have freed them more & more from the aquatic environment. Even so, a number of amphibian species have adaptations that allow them to utilize the terrestrial environment for long periods of time. For example most toads are associated with the terrestrial habitats, while most frogs are associated with living in ponds.
             Toads may be expected to have anatomical or physiological mechanisms that allow them to conserve water more efficiently than frogs during short-term exposure to air. Alternatively, the toads' exploitation of land more due to behavioral adaptations such as burrowing or nocturnal abilities. In this experiment, we have compared the amount of water loss experienced by an aquatic frog species, and a terrestrially adaptive toad species through their skins. The experimental procedure exposes individuals to the two types of amphibians to dry...