Fig. 4. The relationship between mass-specific rate of oxygen consumption and heart rate for three marine iguanas from Santa Cruz, Galapagos at 27 °C (open symbols) and 36 °C (filled symbols). The squares represent data obtained from animals during the pre-exercise period and while walking/running at different speeds, while the circles represent data obtained from the animals during recovery from the preceding exercise (see text for further details). The lines represent the least-squares regressions through all of the data points. At 27 °C, s_O2=0.011fH-0.240, r²=0.76. At 36 °C, s_O2=0.011fH-0.572, r²=0.92.