Bimodal respiration in aquatic and terrestrial apodan amphibians

Abstract

SYNOPSIS. New data on resting metabolism, aerobic capacity, respiratory morphology and bimodal breathing capacities offour caecilian species were combined with previously known data on caecilian and amphibian biology to discern differing or unifying themes of gas exchange within the Gymnophiona and among the Amphibia. Discoveries include 1) a uniform resting metabolism among caecilians that is distinctly lower than that of anurans and urodeles, 2) an aerobic capacity following activity that rivals or exceeds that of other amphibians, and 3) despite previous suggestions to the contrary, a substantial contribution of the skin to respiratory gas exchange, apparently sufficient to sustain the low resting metabolism. In contrast, pulmonary gas transport appears to dominate during metabolic recovery from exercise, which is comparatively fast. The contributing roles of the skin and lungs to this extreme scope of respiratory needs in caecilians are further discussed in light of the structural nature of and circulatory supply to each respiratory bed, and the respiratory properties of caecilian blood. © 1994 The American Society of Zoologists.