Dehydrated snakes reduce postprandial thermophily

Abstract

Transient thermophily in ectothermic animals is a common response during substantive physiological events. For example, ectotherms often elevate body temperature after ingesting a meal. In particular, the increase in metabolism during the postprandial period of pythons - known as specific dynamic action - is supported by a concurrent increase in preferred temperature. The objective of this study was to determine whether hydration state influenced digestion-related behavioral thermophily. Sixteen (8 male and 8 female) Childrens pythons (Antaresia childreni) with surgically implanted temperature data loggers were housed individually and provided a thermal gradient of 25-45 {degrees}C. Body temperature was recorded hourly beginning 6 days prior to feeding and for 18 days post-feeding, thus covering pre-feeding, postprandial, and post-absorptive stages. Each snake underwent this 24-day trial twice, once when hydrated and once when dehydrated. Our results revealed a significant interaction between temperature preference, digestive stage, and hydration state. Under both hydrated and dehydrated conditions, snakes similarly increased their body temperature shortly after consuming a meal, but during the later period of the postprandial stage, snakes selected significantly lower (~1.5{degrees}C) body temperature when they were dehydrated compared to when they were hydrated. Our results demonstrate a significant effect of hydration state on postprandial thermophily, but the impact of this dehydration-induced temperature reduction on digestive physiology (e.g., passage time, energy assimilation) is unknown and warrants further study. Summary statementDehydration suppresses the extent to which python increase body temperature after ingesting a meal, thus demonstrating a physiological conflict between optimizing body temperature and water balance.