Meeting Abstract
Animals from the Crocodilidae and Alligatoridae respond differently to similar diets. We investigated the digestive morphology and physiology of young Alligator mississippiensis and Crocodylus porosus to understand these differences. Allometry of gut length differed; alligators have a steeper increase in intestine mass with body size and crocodiles have a steeper increase in intestine length with body size. Both species showed decreasing intestinal surface area magnification (SAM) from the proximal to distal ends. Although alligators had overall larger SAM, their shorter gut meant that total surface area was not significantly different. Alligators had significantly higher maltase activity, but lower aminopeptidase activity than crocodiles; sucrase activity was barely detectable in both species. These differences in enzyme activity may help explain different responses to captive diets. Both species had high absorption of 3-O methyl d-glucose (absorbed by mediated transport), and also had surprisingly high uptake of l-glucose (absorbed paracellularly), with fractional absorptions as high as those previously seen only in small birds and bats. Absorption rate analysis suggested paracellular uptake was a high proportion of total nutrient uptake in both species. Most paracellular studies to date have been on adults, and we measured juveniles so it is unclear whether paracellular absorption is consistently high within crocodilians or if high values are specific to juveniles.
