What is the purpose of this passage?

Although the Arabian camel or dromedary can go without food for a long while, its hump does not store water as is commonly believed. The real secret of the animal’s unusual ability to store water lies in the fact that very little of the camel’s water is lost by evaporation through the skin. Instead of sweating out great quantities of water, the camel’s body temperature rises, sometimes as much as eleven degrees, to compensate for external heat. When a camel does require water it replaces only the amount lost since its last drink.
   In Egypt, between November and April, the camel can go for three or four months without drinking if it grazes in lush pastures where dew and showers keep the vegetation green, If only dry feed is available, the camel will get thirsty after several weeks—even during January.
   The length of time a camel can go without drinking is greatly determined by time of year, force of wind, heat in the air, intensity of sunlight, amount of reflected heat, kind of feed, weight of the load carried, speed the animal travels and number of hours spent daily in travel.