Metabolic intesnsity and thermal conductance are both inversely related to body weight in homeotherms. The 8-18 g. water shrew (Sorex palustris) dives year-round in cold mountain streams and is thus of considerable physiological interest, because of rapid oxygen consumption, unfavorable surface/volume ratio and light insulation. Project Number 144.
Calder, William A.
"Temperature Relations and Underwater Endurance of the Smallest Homeothermic Diver,"
Jackson Hole Research Station Annual Report: Vol. 1968
, Article 7.
Available at: http://repository.uwyo.edu/jhrs_reports/vol1968/iss1/7