Meeting Abstract

23.3  Friday, Jan. 4  Extreme starvation tolerance in snakes. What makes them so different from other vertebrates? MCCUE, Marshall D; University of Arkansas mmccue@uark.edu

Many snakes demonstrate the ability to survive periods of fasting that can last in excess of one year � a feat rarely matched by other vertebrates. Here I present the results of a series of experiments utilizing six, distantly related squamate reptiles subjected to periods of food deprivation lasting up to six months. Specifically, I compared the morphological, physiological and biochemical responses to starvation observed among these animals with those previously documented among other vertebrates. In some ways the starvation-induced physiological responses of snakes were similar to those documented in other vertebrates (e.g. birds and mammals). For example, [1] the relative water content of their bodies increased and their relative hepatic mass decreased, [2] their circulating glucose and ketone levels changed significantly, but were maintained at levels that were inversely proportional to one another, and [3] they exhibited significant reductions in resting metabolic expenditure. In contrast, these experiments also revealed starvation-induced responses that were either unique or had never been previously documented among vertebrates. For example, [1] starving snakes increased their in snout-vent-length, [2] they differentially catabolized individual fatty acids (sparing essential compounds such as linoleic and arachadonic acids), but did not preferentially spare particular amino acids during protein mobilization, and [3] their excreted nitrogen became gradually enriched in 15N isotopes ultimately approaching levels found in their structural tissues. Most importantly, all of the study animals exhibited endogenous hypometabolic responses (i.e. independent of activity or body temperature) permitting reductions in their standard metabolic rates and ultimately their total energy requirements during food limitation.