Meeting Abstract

P2.17  Friday, Jan. 4  Do Children�s python (Antaresia childreni) eggshells mediate a trade-off between embryonic water balance and metabolic gas exchange? STAHLSCHMIDT, Z.R.*; BRASHEARS, J.B.; DENARDO, D.F.; Arizona State University at Tempe; Arizona State University at Tempe; Arizona State University at Tempe zs@asu.edu

Maintenance of a viable embryonic micro-environment for pythons requires a significant level of buffering from the ambient environment. In addition to maternal brooding, the eggshell provides a certain degree of protection from environmental challenges such as predation and desiccation. However, the shell must allow for sufficient exchange of respiratory gases. In this study we used closed system respirometry and flow-through hygrometry to serially measure oxygen and water exchange rates from parchment-shelled eggs of Children�s pythons (Antaresia childreni). As has been demonstrated in other squamates, respiratory gas exchange across the shell increased nearly exponentially as development progressed, and this likely reflects the increased metabolic rate of the embryo. Interestingly, water loss from the eggs also increased significantly in a non-linear fashion during development. Since the water pressure gradient across the eggshell does not change substantially during development, this increase in water loss suggests a decrease in the resistance of the shell. These data suggest that eggshell morphology may change during development to allow adequate respiratory gas exchange at a cost to egg water balance.