It is no secret that polar bears are one of the most well-known animals on the planet.
Their white fur and huge size make them instantly recognizable, but what you may not know about these beautiful creatures is how they stay warm in their icy habitat.
Polar bears’ thick fur keeps them insulated from cold temperatures, but it can become saturated with water which makes them lose their insulation properties.
They also have a layer of fat under their skin to help keep them warm when they cannot find food or ice to rest on. It’s important for all animals living in arctic climates to be adapted to the harsh environment so they can survive.
In addition to having a coat on top of their skin for insulation purposes, they also have highly vascularized feet which act like built-in snowshoes which help them keep their weight off the ice.
Polar bears are incredible creatures, and it is fascinating to learn how they have adapted to survive in their home.
Polar Bear Fur
Polar bears have two layers of fur. The outer layer, or guard hairs, is made up of long, hollow transparent strands that are filled with air and serve as an insulator. This keeps the bear insulated from the cold Arctic wind and snow and reduces heat loss in water (their feet remain dry).
The inner layer is thick and wooly and provides a safe haven for the bear’s skin, protecting it from parasites and acting as an insulating blanket that conserves body heat.
The outer layer of fur appears white to reflect sunlight, but it actually has a transparent hollow core. This allows visible light to pass through while trapping infrared radiation from escaping. That’s how polar bear fur keeps them so warm in such a cold environment.
Polar bear hair is not just very dense and thick, but also somewhat ‘fluffy’, which provides even more insulation and allows air pockets to form in it.
The hairs of the guard coat are transparent because they do not have the same colored pigments as terrestrial animals, allowing the ultraviolet light necessary for vitamin D synthesis to pass through. The hairs of the undercoat are white and reflect visible light, which also helps to keep them warm.
Polar bear fur is highly hydrophobic (water-repelling), causing moisture from snow or ice to slide off quickly during a swim. This prevents their outer layer from becoming saturated with water, which would cause them to lose their insulating properties. Fur does not absorb liquid and therefore remains effective as an insulator
Polar bear fur is very coarse and can actually be quite irritating to the skin of humans if handled without protection. The fur of a polar bear consists of a layer of long guard hair, ranging in color from clear to yellow or even reddish. A further layer of short underfur provides insulation, and an outer layer of thick waterproof fur
Fur may become on average 2 inches (5 cm) long on their lower parts, but some individuals have been recorded with fur as long as 15 inches (38 cm). The longest polar bear fur on record weighed 110 lbs (50 kg).
Polar bear feet are webbed, partially concealed by fur, and have pads with small bumps on them to provide traction
Polar bears appear white – they look like the ‘typical’ polar bear color is white. However, they are not actually white.
Are polar bears warm-blooded?
Polar bears are warm-blooded animals, so they keep their body temperature at a constant level.
Warm-blooded animals have to maintain a certain body temperature or else suffer from hypothermia.
The only warm-blooded creatures that live in the arctic regions are arctic foxes and humans, who wear plenty of protective clothing to insulate them from the cold.
Polar bears have a high metabolism and need to eat an abundance of food to maintain their body temperature and build fat reserves for times when they cannot catch any prey and therefore cannot eat
Unlike humans who only sweat when it is hot outside, polar bears can sweat, which cools them down or they can pant like dogs to cool down. When they are not active or do not have enough food, they can enter a hypothermic state to conserve energy
Polar bears prefer to hunt seals who are resting on the ice, instead of swimming after them because this is less energetically demanding. They have evolved long claws that help them to grip onto ice to make it easier to catch prey
When a polar bear is born, its underfur isn’t completely developed, so the cub has poor insulation until it grows enough hair. As adults, polar bears are too big for their mothers to keep them warm with body heat alone, so they huddle together in sleeping bags of fur when they sleep.
Polar bears spend the winter in dens dug out of snowdrifts. They huddle together with other bears during this time to conserve heat and sleep as much as 10 months of the year.
Polar bears have a few ways to regulate their body temperature. They can shiver and create heat by contracting muscles rapidly without moving, they can pant like dogs to cool down, or they can sweat through their paw pads. When it is hot outside, polar bears can also enter a hypothermic state to conserve energy.
The layer of fat beneath the skin provides insulation when they are in their dens over winter. Many scientists believe that polar bears could not survive if sea ice continues to melt because they will have nothing to rest on while they sleep and nothing to break up the water as waves, which would make it harder for them to catch prey.
Polar bear fur is very coarse and has a hollow core that traps air to provide insulation from the cold
Fur may become on average 2 inches (5 cm) long on their lower parts but some individuals have been recorded with fur as long as 15 inches (38 cm). The longest polar bear fur on record weighed 110 lbs (50 kg)
