How do animals not freeze in extreme cold?

 Introduction

    Peace be upon you, and God’s mercy and blessings. When we were young, we got a general idea in our science classes about the weather conditions in Egypt, and we all memorized the famous phrase about Egypt’s weather - I am from Egypt - : hot and dry in summer, warm and rainy in winter. Regardless of the fact that this is not exactly what happens nowadays and the world has changed, we still don’t experience the extreme cold as it is in some countries, where people spend most of their lives in the snow. As humans, our bodies have a way to defend themselves in cold conditions, even if for short periods. 

In such cases, the body reduces the warm blood flow to the extremities to conserve heat so that it goes to the more important organs like the brain, heart, and lungs, etc. This is the reason why our extremities turn white or blue in the cold. However, if the exposure to cold is for long periods, our body can’t continue this way. That’s why people living in very cold countries understood the matter and started doing things to avoid the low temperatures. 

You’ll find them wearing several layers of clothing, which are heavy and padded or fur-lined. But here’s a question that poses itself: have you ever seen an animal from those living in these cold regions wearing heavy clothes? Well, we might say it’s normal; they don’t need to wear them since their bodies are covered with fur or long hair that keeps them warm. Their hands and feet, I’ve never seen a dog wearing boots or wool socks before. And here, we’re not talking about sled dogs that humans dress in boots. We’re talking about animals that live naturally in the wild, and yet their feet don’t freeze in extremely low temperatures.

Snow’s Impact on Animal Limbs: 

       The first thing that differentiates animals from humans is that they have four limbs, which means their weight is distributed over four points, not two, like us. This changes the effect of snow on their bodies. Additionally, the animals living in frozen regions are not new there; they are successive generations of animals that have lived in that place for hundreds or thousands of years. Consequently, their bodies have started to adapt to the situation there differently from animals living in warmer places. For example, the skin at the extremities of animals living in frozen places is thicker than that of animals living in warmer places, so that the layers of skin act as an insulator for heat. But still, is this enough to mean that their feet don’t freeze?

Heat exchange in the limbs of animals

What helps these animals in their fight against the cold is that they have many blood vessels in their extremities. All living creatures have blood vessels distributed throughout their bodies in a certain way according to the type of creature. However, the blood vessels in animals living in frozen places are a bit different from the norm. Firstly, they are faster than the circulatory system we have as humans, providing more warm blood to the extremities, as if there’s a constant warm stream of blood flowing back and forth all the time, like the animal is walking with a heater on its legs. 

In a study conducted by the Japanese researcher Hiro Yoshi N. Namiyo, an expert in animal anatomy at Yamazaki University in Tokyo, Hiro noticed that dogs in Japan cope normally with different temperatures. For example, in summer, the asphalt temperature can reach 66 degrees Celsius, and in winter, the temperature can drop to nine below zero—a tremendous difference between the two temperatures. Yet, the dogs go about their business normally and are not bothered as if they don’t have any problems. And here we are talking about ordinary dogs, so imagine the animals whose entire lives are in frozen countries. 

Hiro and his team began to photograph the blood vessels in the extremities of these animals using an electron scanning microscope and discovered that the veins surround the arteries themselves and are arranged in a way that allows them to exchange heat with each other in a process called thermal exchange. The arteries in it transfer heat to the veins, which are cooler, which means that the blood returning to the animal’s heart does not return cold but returns warm, and therefore the animal remains warm from within.

Animal Insulation Against Cold:

     In addition, the hair, fur, or skin on the outside of an animal’s body helps it retain heat inside, just like thermal insulation. This is similar to the concept of a tea thermos. Therefore, the skin of the animal, especially at the extremities, also remains constantly warm. This warmth is sufficient to prevent the animal from getting frostbite. Frostbite occurs when the skin is exposed to very low temperatures for a long period. 

The extreme cold forms ice particles inside the skin cells, leading to pain, redness, and inflammation of the skin. If the situation continues without treatment or warming up quickly, it could lead to amputation of the affected limb. However, this does not happen in animals for the reasons we mentioned. Because the body has an insulating layer on the outside, it does not lose all its heat during the warming process. Therefore, the blood keeps flowing, and every time it cools down, it warms up again with new blood coming from the heart. This makes us say ‘SubhanAllah’ (Glory be to God) for the precision of creation. 

The blood vessels do not work randomly; they contract and expand very precisely according to the required temperature and even according to the specific part of the animal’s body that needs warming. This helps the animal maintain a warm body temperature, not just at the extremities. Therefore, no matter how much the animal walks on the snow, its feet do not get frostbite. This method of warming is present in most animals that live in frozen regions, despite the differences in the shape of their limbs.

Seal and Fox Winter Adaptations:

     Take the seal, for example, which spends its life crawling on the snow or diving into near-frozen water, or the arctic fox, which has the same reciprocal heating system in its extremities. Add to that, other animals have an additional feature; the wolf, for instance, has long hair that traps air between it and the outer skin layer. This air heats up from the body’s warmth but remains stuck to the skin, reducing the amount of heat that is normally lost. Although domesticated dogs have the same heating system, it does not function fully in animals that live in warm or moderate climates. Therefore, animals accustomed to warm weather, if they go to a very cold place, might experience the same as us: they could get frostbite, freeze, or even die.

Birds’ Heat Preservation Techniques:

And now a question arises: does this apply only to animals, or could it also be found in birds? Birds are creatures that enjoy being together; you’ll often find them huddled together to maintain their body heat. The idea here is that birds have very small legs, which are more susceptible to freezing. Their small size means they don’t have as many blood vessels as larger animals. 

So, what do they do in this case? Take penguins, for example, even though they are birds, they may not fly, but they have the same concept of heat exchange we talked about, just in a different way. When the heart pumps blood into the penguin’s veins, it starts out warm, yes, but it loses its heat quickly. That’s why when it reaches their feet, their feet remain colder than the rest of their body. But when the blood returns to the heart, it regains what it lost, and thus the heat remains preserved around the heart and the important organs in the body. 

Conclusion:

Finally, now you know why animals don’t experience this in frozen places. So if you ever get the chance to go to one of these places, don’t underestimate the situation. Take plenty of heavy clothing with you and keep yourself warm.