Comparative skin permeability of neonatal and adult timber rattlesnakes (Crotalus horridus)

Skin permeability and lipid content were determined using shed epidermis of neonatal and adult timber rattlesnakes (Crotalus horridus) from the Coastal Plain Pine Barrens of New Jersey and from the Appalachian Mountains of northern Pennsylvania. Differences between populations due to habitat and within populations due to age were tested. Skin permeability was not found to differ according to locality (P > 0.05), but rates were significantly different for age. Permeability of adult epidermis was greater than that of neonates (P < 0.01). Lipid content did not differ by locality (P > 0.05), but differed between ages, paralleling the results found for permeation rates. Neonate sheds had a greater amount of extractable lipids than adult sheds (P < 0.01). Despite the lower skin permeability of neonates, our estimates indicate that the percentage of their total body water content lost per hour may still be 2.2 times that of adults. Resistance to cutaneous water loss may be advantageous to neonates given their relatively large surface area-to-volume ratio.