CASON, E.M.; FARRAR, E.S.; VLECK, D: Passage time through anuran larval intestines

Algae and diatoms are passed through the intestine of anuran larvae and remain relatively unscathed. They are in such good condition that they can be identified to species. This provokes questions about tadpole digestive mechanisms and efficiency. As an initial step toward investigating these questions, we began with defining and measuring passage time. We measured passage times through the intestines of five species of tadpoles: Bufo americanus, Hyla versicolor, Pseudacris triseriata, Rana pipiens, and Xenopus laevis. We determined the time interval between ingestion of fluorescent microspheres and their excretion in feces. Using this method, we found passage times ranged from 2.5 to 12.6 hours. With the exception of Xenopus laevis, tadpoles with shorter snout-vent lengths had shorter intestines and shorter passage times.