COMPARATIVE STUDIES OF THE OXYGEN CONSUMPTION OF THREE SPECIES OF NEOTENIC SALAMANDERS AS INFLUENCED BY TEMPERATURE, BODY SIZE, AND OXYGEN TENSION

¹ Biology Department, Southwest Texas State College, San Marcos, Texas, and Marine Biological Laboratory, Woods Hole, Massachusetts

1. Three species of neotenic salamanders of the genus Eurycca were collected from their specific, though not widely separated, habitats on the escarpment region of the Edwards plateau in south central Texas.

2. Utilizing standard Warburg manometry, oxygen consumption was determined for each of the species (with and without shaking) at 15, 20, 25. and 30° C. Maximal respiratory rates were exhibited by Eurycea neotenes at 30° C., by Eurycea nana at 25° C., and by Eurycea pterophila at 20° C. Mechanical stimulation (shaking) increased the rate of oxygen uptake but did not alter the shape of the R/T curves. For E. nana and E. neotenes the temperature at which the maximal metabolic rates were observed appeared to be correlated with the temperature characteristics of the natural environment.

3. There is a decrease in metabolic rate with increasing body size. The specific relationship is in good agreement with previously reported values.

4. All three species of salamanders seem to be intermediate between oxygen conformers amid regulators, in that the rate of oxygen consumption is dependent on oxygen concentration (up to the oxygen content of air), but not in a strictly linear manner.