The Herpetological Journal

pp.60-64

Authors: Razi Dmi'el , Gad Perry, Ann Belinsky And Ralph A. Ackerman

Abstract: We studied the effects of incubation substrate and its water content on egg water uptake, incubation duration, and hatchling mass in the diced water snake Natrix tessellata. Egg water uptake was highest in sand (the substrate with the highest thermal conductivity) and lowest in air (which had the lowest thermal conductivity). Water uptake was independent of initial egg mass. Incubation duration was correlated with substrate type and water content. Hatchling mass was independent of initial egg mass, but there was a weak negative correlation with total water uptake and with length of incubation. Wet mass of hatchlings incubated in air was greater than those incubated in sand or vermiculite. A greater increase of water uptake by eggs incubated in the most thermally conductive substrate (moist sand) suggests transport of water vapour, rather than liquid water, as the mechanism of transport across the membranes of parchment shelled eggs.