As the first class of vertebrates to widely colonize terrestrial environments they present a variety of interesting adaptations regarding their ability to obtain water when it is available but to tolerate dehydration when water is not available. One area of active research is to elucidate intrinsic and extrinsic factors that regulate water absorption behavior by desert toads.
Toads absorb water across specialized areas of their skin rather than drinking orally.
While absorbing water across their skin, the animals assume a characteristic posture, termed the water absorption response, in which the area of skin pressing against a moist surface is maximized. Ongoing studies are directed at identifying areas of the brain associated with the regulation of thirst and drinking. In addition we have found that toads avoid hydration behavior when given solutions that are too concentrated to permit osmotic water gain across their skin. In particular, they can taste sodium chloride specifically by way of ion channels in the outer facing membrane of epithelial cells in their skin. In this regard, the skin is performing functions that are similar to those of the taste buds of vertebrates that drink water orally.