Phenotypic flexibility in cutaneous water loss and lipids of the stratum corneum.

When vertebrates invaded land during the Carboniferous period, they were exposed not only to new ecological opportunities but also to a desiccating environment. To maintain cellular water homeostasis, natural selection modified the integument of pioneering terrestrial animals, enabling them to reduce water loss through the skin. In desert environments, where ambient temperatures (T(a)) can reach 50 degrees C, relative humidities are low and drinking water is scarce, integumentary modifications that reduce cutaneous water loss (CWL) could be fundamental to survival.