Fig. 5. Relationship between body mass (M_b, g) and standard metabolic rate (SMR, ml O₂ h^-1) for (A) euthermic and (B) hypothermic mammals, normalised to a body temperature of 36.2°C (see text for details): a Q₁₀ of 2.8 was used for euthermic mammals, 2.4 for mammals in daily torpor (filled circles) and 2.2 for hibernating ones (unfilled circles). Equations of the regression lines: euthermic mammal SMR=4.14M_b^{0.675±0.013 (95% CI)}, r²=0.96, N=469; torpid mammal (solid line) SMR=4.81M_b^0.67±0.1, r²=0.86, N=30; hibernating mammal (broken line) SMR=0.669M_b^0.87±0.08, r²=0.90, N=59. Data for euthermic mammals from White and Seymour (2003), data for hypothermic ones from Geiser (1988).