Water Uptake from Air in a Desert Thread Snake, Myriopholis macrorhyncha

AbstractSquamates are adapted to thrive in extreme deserts thanks to, among other mechanisms, the water-conserving characteristics of their integument. Yet very small-bodied species, such as the fossorial desert thread snake Myriopholis macrorhyncha (∼1 g), face challenges because of their high relative surface area entailing high evaporative water loss. Fossorial snakes avoid dry periods by retreating underground, which can reach high humidity even in the desert habitat of M. macrorhyncha. We measured evaporative water loss of three individuals at 25°C and three different ecologically relevant humidity conditions. We found low water loss at 70% relative humidity (RH) compared to the high water loss in dry air (near 0% RH). Interestingly, we found apparent water absorption at 97% RH, confirmed by both respirometry and equivalent gains in body mass following this treatment. This suggests an adaptation allowing the snake to acquire water from the atmosphere during its retreat to subterranean burrows and ant nests. Coupled with other water-conserving strategies, such as discontinuous gas exchange to reduce respiratory water loss, this strategy could be crucial for survival in arid environments where water is scarce.