Meeting Abstract
Some mammals and birds rely on passive, paracellular absorption of small, water-soluble nutrients (e.g. small carbohydrates) as a significant component of overall absorption of those nutrients. This is particularly important in small, flying mammals and birds, possibly as a means to fuel high metabolic demands despite small guts and fast digesta passage. But how important is paracellular absorption of those same nutrients for low metabolic rate taxa like reptiles? Our studies on herbivorous lizards and crocodilians suggest that paracellular nutrient absorption in these low metabolic demand vertebrates represents a relatively small, but significant proportion of total absorption, particularly in younger animals whose rapid growth may increase metabolic demands. This appears to support the hypothesis that paracellular absorption provides a low-cost source of additional energy for some species or life stages. At this time, paracellular absorption has been measured only in a few ectothermic species, and there have been few studies of ontogeny of paracellular absorption, so many questions about patterns in reptilian paracellular absorption remain unanswered
