Microcalorimetric Investigations on the Energy Metabolism of Lizards

The energy metabolism of three lizard species (Podarcis milensis, Podarcis muralis and Lacerta agilis) was investigated by means of microcalorimetry and polarography over the range of environmental temperatures between 17 and 35 °C encountered by active lizards during summer in Europe. In non-stimulated animals, the maximum and mean heat production rates were highest around 30°C for all species and amounted to 3.9±l.lmWg⁻¹ and 2.1±0.5mWg⁻¹, respectively. Resting metabolism contributed approximately 60% to the mean routine heat dissipation; the remainder originated from locomotory activity, 43% of which was based on anaerobic energy metabolism. From simultaneous determinations of heat dissipation and oxygen consumption, an average oxycaloric equivalent of 18.6±3.2 J ml⁻¹O₂ was calculated, which rose to 26.6±7.1 J ml⁻¹O₂ during short bursts of locomotion.