Meeting Abstract

100.1  Wednesday, Jan. 7  To Regulate or Not to Regulate; Stomach Acid Production in Amphibians and Reptiles BESSLER, Scott M.*; SECOR, Stephen M.; University of Alabama; University of Alabama besslers@gmail.com

For amphibians and reptiles there is an adaptive link between feeding habits and the capacity to regulate gastrointestinal performance. Frequently feeding species maintain stable intestinal performance between feeding bouts, whereas infrequently feeding species widely regulate intestinal performance with each meal. Given the apparent high cost of gastric acid production, we predicted a similar pattern; frequently feeding species maintain acid production between meals and infrequently feeding species shut down acid production during their long periods of fasting. To explore this hypothesis, we measure gastric pH from fasted and digesting individuals for 11 frequently feeding species (anurans, lizards, snakes, and alligator) and 8 infrequently feeding species (Xenopeltis, boas, and pythons). All frequently feeding species, with the exception of the snakes Nerodia rhombifer and Homolopsis buccata, maintained an acidic pH (pH = 1.1-2.5) within their stomachs while fasting and thus experience no significant change in gastric pH with feeding (pH = 1.0-3.0). In contrast, all infrequently feeding snakes greatly reduced acid production while fasting (pH = 5.0-7.7) and thereby had to rapidly increase acid production after feeding. During the digestion of their large intact meals, gastric pH was maintained at 1.5-2.5. For infrequently feeding snakes, the ability to downregulate both gastric and intestinal performance apparently serves to reduce their energy expenditure during their long predicted episodes of fasting. For the majority of frequently feeding amphibians and reptiles, as well as for fishes and mammals, the selected strategy is to maintain constant acid production between meals.