A comparative study of evaporative water loss and epidermal permeability in an arboreal snake, Opheodrys aestivus, and a semi-aquatic snake, Nerodia rhombifera

1. 1. Evaporative water loss was compared in two snake species, the arboreal Opheodrys aestivus and the semi-aquatic Nerodia rhombifera. 2. 2. Rates of water loss were significantly higher ( P < 0.01) in N. rhombifera ( X ̄ mg H 2 O/cm 2/ hr = 0.666 ) than in O. aestivus ( X ̄ mg H 2 O/cm 2/ hr = 0.209 ). 3. 3. Shed epidermis of N. rhombifera was significantly ( P < 0.001) more permeable ( X ̄ mg H 2 O/cm 2/ hr = 0.764 ) than that of O. aestivus ( X ̄ mg H 2 O/cm 2/hr = 0.476 ). 4. 4. Following lipid extraction the permeability of shed epidermis increased in both species with the greater increase occurring in O. aestivus. 5. 5. The efficacy of epidermal lipids in reducing cutaneous water loss may be an important adaptation to an arboreal environment in O. aestivus.