Ontogenetic Changes in Diet and Intestinal Morphology in Semi-Terrestrial Tadpoles of Nannophrys Ceylonensis (Dicroglossidae)
Semi-terrestrial tadpoles of the Sri Lankan dicroglossid rock frog (Nannophrys ceylonensis) feed by scraping the surface microfilm from the wet rocks on which they live. Gut content analysis of 40 tadpoles revealed microflora, microfauna, detritus, and mineral particles. Conspecific eggs and tadpoles were rarely also found in the tadpoles' guts. Absolute gut length decreased by 59% between Gosner stages 26 and 42, and the number of gut coils decreased as well. Tadpoles of N. ceylonensis shift from primarily herbivory to primarily carnivory as they develop, with the greatest shift occurring from Gosner stages 32 to 34. This dietary shift is correlated with a decrease in the length of the gut and the number of gut coils. Precocious metamorphosis of the alimentary tract to accommodate a carnivorous diet may facilitate tadpole survival and growth in a heavily shaded terrestrial environment with relatively low primary productivity.Abstract
Morphological measurements of tadpoles of Nannophrys ceylonensis and percent occurrence of food items found in their intestines during larval development. Relative gut length is gut length divided by snout–vent length. The “other” category is comprised of rarely found items described in the dietary analysis section of the results. Each point represents an independent mean for that developmental stage. Points have been connected with a line to better illustrate trends. The error bars on the morphometric data in the bottom graph are ± two standard errors.
Contributor Notes
Section editor: J. F. Webb.