Camels require very little water because they are able to tolerate relatively large changes in their body temperature. While humans keep their body temperatures constant to within one or two Celsius degrees, a dehydrated camel permits its body temperature to drop to 34.0oC overnight and rise to 40.0oC during the day. (Note: The specific heat of a camel or other mammal is about the same as that of a typical human, 3480 J/(kgAc?1...K). The heat of vaporization of water at 34oC is 2.42 Af- 106 J/kg.)
To see how effective this mechanism is for saving water, calculate how many liters of water a 400 kg camel would have to drink if it attempted to keep its body temperature at a constant 34.0oC by evaporation of sweat during the day (12 hours) instead of letting it rise to 40.0oC.