BAGLEY, J.C.*; SECOR, S.M.; University of Alabama, Tuscaloosa; University of Alabama, Tuscaloosa: The allometry of metabolic and intestinal performance for the marine toad and diamondback water snake

To investigate the potential interactions between the allometry of metabolic rates and intestinal performance, we assess the effects of body mass on standard metabolic rates, intestinal mass, intestinal nutrient uptake rates, and total intestinal nutrient uptake capacities of the marine toad (Bufo marinus) and diamondback water snake (Nerodia rhombifer). Standard metabolic rates of marine toads (2.4- 950 g) and water snakes (7 � 1800 g) scaled (log-log) with body mass with mass exponents of 0.70 and 0.90, respectively. For both species, wet mass of the small intestine scaled with a mass exponent of 0.81. Mass-specific intestinal uptake rates of the amino acid L-leucine and L-proline and of the sugar D-glucose, measured using the everted sleeve technique, tended to decline with body mass. Total intestinal capacity for nutrient uptake, a function of intestinal mass and mass-specific rates of uptake, scaled with exponents between 0.55 and 0.74 for marine toads and between 0.60 and 0.83 for the water snakes. A potential relationship between the allometry of metabolic rate and intestinal performance is suggestive for the toads, but appears less likely for water snakes.