Crocodilians, like other reptiles, regulate their body temperatures by a combination of behavioral and physiological mechanisms. Behaviorally, they seek warm surface water or bask when cool and avoid overheating by the evaporation of water from their dorsum, evaporation of water by gaping or by retreating to deep, cool water. Physiologically, crocodilians increase cutaneous thermal conductance by increasing blood flow to the skin (and subdermal musculature) during warming. This hastens the warming process. Cutaneous blood flow is reduced during general cooling and locally if the body temperature exceeds skin temperature. This enables crocodilians to increase body temperature significantly while basking in cool shallow water. Large crocodilians appear to be able to alter their rates of heat exchange to a larger extent than small ones and they can do so with less cardiovascular involvement. Large crocodilians, with their lower surface/volume ratio, are capable of producing sufficient metabolic heat to elevate their body temperature above water temperature.