Effect of developmental stage and body size on oxygen consumption of anuran larvae: A reappraisal

The rate of oxygen consumption (V̇ ) varies throughout metamorphosis in larvae of anuran amphibians. To determine whether variation in V̇ is best explained by variation in developmental stage (S), dry body mass (M), or their interaction, I measured V̇ in developmental series of four species. In all species M accounted for most (59–90%) of the variation in V̇ . Developmental stage has relatively little effect on V̇ after appropriate correction for differences in M among samples; S accounted for no more than 2% of the variation in V̇ in two genera ( Bufo , Rana ) and no more than 7% in a third ( Hymenochirus ). Late stages of metamorphosis were not examined in these larvae. In Xenopus larvae, S has little effect upon V̇ until late stages of metamorphosis, in which some but not all larvae had reduced V̇ . The general relationship between V̇ and M in anuran larvae at 25°C is V̇ = 3.1 M 0.827 , where V̇ is in μl O 2 STPD ·hr −1 and M is in mg. Because the exponent of M, 0.827, is less than 1.0, expression of V̇ as V̇ ·M −1 fails to correct for differences in M in statistical analyses. Most prior studies of larval V̇ require reevaluation because of statistical and methodological problems.