The body is a marvellous machine. It's capable of wondrous feats that we simply take for granted. For example, how often do you think a camel thinks about how it is able to withstand such extreme heat conditions? How often is a polar bear grateful for its carefully crafted fur? Many other animals withstand conditions just as extreme and seem to do just fine; in fact they seem to thrive in them. Humans seem to be the only animals that struggle with their environments. We are able to regulate our bodies' temperatures to a degree (pun intended) but we still rely on machines to keep us comfortable.
As mentioned, camels are designed to withstand extreme heat. Their body temperatures range from 34 degrees Celsius at night to 41 degrees Celsius during the day. They only begin to sweat once this threshold has been breached thus preserving precious water. When they do sweat, it evaporates right at the surface of their skin so that it cools the body efficiently. This is also important in the conservation of water; it can save up to 5 liters of water a day. All this conservation of water during perspiration, camels can withstand at least a 25% weight loss due to sweating, while most mammals can only withstand 3-4% before cardiac failure results from dehydration and thickened blood. Camels' blood stays hydrated until the 25% limit is reached.
Their thick coats also play an important role, reflecting the sunlight and insulating them from the heat radiating from the sand. And if you thought that their long legs were there just for laughs, think again, they serve to keep them further away from the heat of the ground. Their long eyelashes protect their eyes during sandstorms and their nostrils are sealable. How cool is that? Sealabale nostrils! The pads on their feet spread as they step, preventing them from sinking into the sand. Camels are the ships of the desert; there can be no doubt about that.
What about polar bears? Well, what about them? They live in the arctic, they swim in the arctic and apparently sometimes they get so hot that they have to cool down. This is the truth. They are so well insulated that sometimes they overheat, which is why they only run when they have to and why they slide down snow on their bellies, they are literally chilling. They swim to cool down on warm days or after physical activity. Excess heat is also released in areas where fur is absent or blood vessels are close to the skin eg the muzzle, nose, ears, footpads, inner thighs, and shoulders. On days when they are not swimming to cool down but to hunt, and the water is freezing, a thick layer of blubber keeps them warm, their hair is also designed so that water is easily shaken off as well as any ice that may start to form. The hair sticks together when wet and effectively keeps the bear dry when it is swimming. The hairs are hollow and channel ultraviolet light down to the bear's skin, which is black. The skin absorbs the sunlight as heat energy. A pretty nifty trick in anyone's book. Another cool feature that polar bears comes equipped with are nostrils that close when under water. And now we have linked polar bears and camels. They both have sealable nostrils. A feature that I think rocks this world and the next.
Human beings do not have sealable nostrils, a much lamented fact, which scientists have probably tested to rectify many times in many labs across the world. To be completely denied of course. Instead we have air conditioners to keep us cool and heaters to keep us warm hanging on the season. It must be said, who ever invented air conditioners was a genius and should be knighted, or sainted for his troubles.