Oxygen uptake in air and water in the air-breathing reedfish Calamoichthys calabaricus: role of skin, gills and lungs.

Abstract

The reedfish Calamoichthys calabaricus (Smith) is amphibious, making voluntary excursions on to land (in a simulated natural environment) an average of 6 +/- 4 times/day for an average duration of 2.3 +/- 1.3 min. Oxygen uptake is achieved by the gills, skin and large, paired lungs. In water at 27 degrees C, total oxygen uptake is 0.088 ml O2/g.h. The lungs account for 40%, the gills 28%, and the skin 32% of total VO2. Total oxygen uptake during 2 h of air exposure increases from 0.117 ml O2/g.h to 0.286 ml O2/g.h, due largely to an enhanced lung VO2 and a small increase in skin VO2. Calamoichthys is both capable of aerial gas exchange and adapted to maintain O2 uptake during brief terrestrial excursions.