The bear is considered the largest predator on earth; this species originated on the planet about 6 million years ago.

All about bears

The body length of the predator, depending on the species, varies from 1.2 to 3 meters, weight can reach up to 1 ton, the jaws are very powerful, and the limbs are slightly curved and short.

The bear can reach a speed of up to 50 km/h, with the help of large and sharp claws it can easily climb a tree, tear apart its prey, and pull out plant roots from under the ground.

Most bears are good swimmers.

Life expectancy can reach 45 years. They have a good sense of smell.

The bear's fur is very hard and thick, the color has various shades from brown to black, white or black and white, and gray hair may appear with age.

The tail of predators is almost invisible, only in the panda it is clearly pronounced.

Varieties and photos of bears

Zoologists distinguish eight main species of bears and many varieties:

Brown bear

His external characteristics consist of: a large head, a rather powerful body, small ears and eyes, a tail almost invisible, large paws with large claws.

The color of six, depending on the habitat, can be brown, gray or even reddish. Brown bears are found in North America, Europe, Asia, and the Scandinavian Peninsula.

Polar bear (white)

It is the largest predator of the bear family: the weight can be more than one ton, the body length is about three meters, the head is flattened, and the neck is long. The coat color can be pure white or slightly yellowish.

The fur on the soles of the paws is very thick, which allows the bear to easily walk on ice without slipping.

Feels comfortable in the water and swims well. Lives in regions of the Northern Hemisphere.

Baribal (black)

Unlike brown bear It is smaller in size and has a very black coat color. It can be more than 2 meters long, the female is 1.5 m.

Elongated muzzle, long paws, short feet, gray or brown color. Lives in the territories of Alaska, Canada, Mexico.

Malayan bear

Very small, as a rule, body length no more than 1.3-1.5 m, height at the withers about 0.5 m. Stocky build, wide muzzle, small ears. The paws are high, the feet are long with large claws.

The bear's fur is very hard, black-brown in color, and has a white-red spot on its chest. It can be found in Thailand, China, Indonesia.

White-breasted bear

It does not differ in large size; the male reaches a length of up to 1.7 m, and the female is even smaller. The bear's body is covered with dark brown or black silky fur; this bear also has very large ears and a sharp muzzle.

Distinctive feature This species has a white or slightly yellowish spot on the chest. These representatives of the bear family live in Afghanistan, Iran, and countries Far East, as well as in the mountains of the Himalayas.

There are still a huge number of subspecies, which can be listed and described ad infinitum. Bright representatives of predators of this species can be called such bears as: Spectacled bear (Tremarctos ornatus), Sloth bear (Melursus ursinus), Bamboo bear commonly known as panda (Ailuropoda melanoleuca), and many other.

Habitat

The habitat of these graceful representatives of the fauna is very diverse; they are present on all continents. They mostly prefer to settle in forests and lead a solitary lifestyle.

All types of bears are attached to their territory, where they hunt and stay for the winter, the only exception to this rule is the polar bear.

Menu for the predator

Bears eat absolutely everything as food, it can be berries and mushrooms, nuts and various roots, all kinds of meat and fish; ants, bee larvae and honey can serve as a delicacy for animals; there are also vegans among bears, these are pandas and koalas.

Among all the diversity of bears, the pure predators are again polar bears, whose diet includes only fish and meat.

How is a bear animal born?

Mating of bears occurs during the mating season (this is a different period for each species). Also, depending on the species they belong to, the gestation period of female bears varies and lasts from 180 to 250 days.

Childbirth occurs during wintering, when the animal hibernates. The female gives birth to 1-4 cubs, weighing from 450 grams to half a kilogram, they have neither teeth nor hair.

Breastfeeding lasts about a year, and cubs from the previous litter (parents) help the mother in raising the babies until they reach the age of two.

Bears reach sexual maturity after a minimum of three years.

In order for the bear to feel most comfortable, spacious enclosures are created and a habitat as close to natural as possible is created.

In addition to trees, stones and various wooden structures, such an enclosure must be equipped with a sufficiently large swimming pool.

The diet must be kept in accordance with the season and include all those elements that animals receive in their natural habitat.

Photo of a bear

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What color is a polar bear's fur actually?

Polar bear Characteristic features that distinguish a polar bear from its relatives are relatively long legs, a narrow chest, a long neck and a rather small flat head. The skin, nose, lips, paw pads and eyes are black, and the coat color varies from white or grayish to yellowish or yellowish-red. The shade of a fur coat often depends on the season, age (bear cubs have whiter fur coats than adults) and other factors, for example, in summer the fur may turn yellow due to constant exposure to sunlight.

The polar bear is the largest representative of the predatory order. Its length reaches 3 m, weight - 800 kg. Typically males weigh 400-600 kg; body length 200-250 cm, height at the withers up to 160 cm. Females are noticeably smaller (200-300 kg). The smallest bears are found in Spitsbergen, the largest in the Bering Sea.

The polar bear is distinguished from other bears by its long neck and flat head. His skin is black. The color of the fur coat varies from white to yellowish; In summer, the fur may turn yellow due to constant exposure to sunlight. The polar bear's fur is devoid of pigment color, and the hairs are hollow. There is a hypothesis that they act as light guides, absorbing ultraviolet rays; in any case, in ultraviolet photography, the polar bear appears dark. Due to the structure of the hairs, a polar bear can sometimes turn green. This happens in hot climates (in zoos), when microscopic algae grow inside the hairs.

Do you know that... "Umka" in Chukchi means a bear, or more precisely, an "adult male polar bear"

Many of us believe that polar bears have white fur, but in reality this is not so: the animals’ hair, like the undercoat, is transparent and completely colorless. And they appear white to us because there is an air pocket inside each guard hair. When a light beam consisting of all the colors of the rainbow hits the wool, the colors from the air pockets are reflected and mix to create a white color.

Depending on the season and the location of the Sun, the animal’s fur can be not only white, but yellow or brown (bears living in captivity can even be green due to algae in artificial reservoirs). But if someone managed to shave off all the fur from an animal, they would be surprised to discover that the skin of a polar bear is black. The dark skin helps absorb and retain the sun's rays, protecting the predator from the Arctic frosts.

The largest bear is called a white or polar bear. carnivorous mammal an animal that lives on the surface of the earth (second only to the elephant seal). He is the closest relative of the brown bear and belongs to the bear family. There are about fifteen species in nature polar bear, and the total number of animals is about twenty-five thousand.

You can meet these animals in the subpolar latitudes of the northern hemisphere, starting from Newfinland and ending at 88° N. sh., and they live on ice floating in the Arctic off the coast of Eurasia and America, so they can only be classified as terrestrial inhabitants only conditionally.

If you think about what natural area Polar bears live here, you might be surprised: they are the only large predators in the Arctic, ideally adapted for normal existence in polar latitudes. For example, during snow storms they dig holes in the snowdrifts, lie down in them and, without going anywhere, wait out the elements.

The size and weight of these animals largely depend on their place of residence: the smallest animals according to description live on Spitsbergen, while the largest ones live in the Bering Sea. The average height of a bear at the withers reaches about one and a half meters, while the weight of males significantly exceeds the weight of females:

• The weight of males ranges from 400 to 680 kg, length - about three meters (the weight of large lions and tigers does not exceed 400 kg);
• The weight of females ranges from 200 to 270 kg, the length is about two meters.

According to the description, the polar bear differs from other representatives of its species by its greater weight, powerful sloping shoulders, flat head and longer neck.

There is fur on the soles of the paws, which allows the animal not to slip and freeze. There is a membrane between the toes, and the structure of the paws allows polar bears to swim gracefully, gracefully and quickly. Large curved claws are not only capable of holding even strong prey, but also allow it to easily move on slippery ice and climb over blocks.

It is noteworthy that these animals are quite capable of reaching speeds of up to 10 km/h and swimming about 160 km without stopping. They are also very good divers and can stay underwater for about two minutes.

The polar bear does not freeze thanks to a thick, about 10 cm, layer of subcutaneous fat on the back, back of the body and hips, as well as very warm fur, which retains the heat generated. The predator's fur is very thick and dense; it not only reliably retains heat, but also protects the animal's body from getting wet, and its white color makes it possible to camouflage perfectly.

The teeth of polar bears are also noteworthy: in cross-section, they form annual circles of two cement layers. The tooth is tightly attached to the jaw, as the root of the teeth is connected to it by a layer of cement that grows throughout the bear's life. At different times of the year, the layer grows differently and seems to consist of two parts: the winter layer is thinner than the summer layer, which is located above it, and the older the animal, the smaller the distance between the rings.

Way of life

Although polar bears give the impression of being a clumsy animal, in fact they are very fast, agile, and excellent at diving and swimming, both on land and in water. For example, when escaping danger, a polar bear can move at a speed of about 7 km/h without any problems. They are capable of covering considerable distances: the record for the longest movement was recorded for a polar bear, who, together with her baby, swam 685 km across the sea from Alaska to the north in search of a new home.

The main reason why she did this was that the place where the polar bears lived was no longer suitable due to the melting of the ice floes: the seals left their place of residence. Unfortunately, the cub died during such a nine-day swim, and her weight decreased by twenty percent.

Despite their ability to develop high speeds, polar bears still prefer to move slowly and without haste: although temperatures in the Arctic can drop to minus forty, these predators usually experience problems not with freezing, but with overheating (especially when running).

Despite the fact that polar bears are solitary animals, they do not fight for their territory and have a positive attitude towards other representatives of their species: they often colonize an area in groups and roam with each other. In the absence of food, they are able to eat their relatives.

Animals also do not live in one place for a long time and move along with the ice, which floats closer to the pole in the summer, and to the south in the winter, while once near the continent, the predator comes to land. The polar bear prefers to be either on the coast or on glaciers, and in winter it can easily set up a den for itself at a distance of 50 km from the sea.

It is worth noting that the female sleeps the longest during pregnancy (two to three months), while males and non-pregnant female bears hibernate for a short period, and not every year. When they go to bed, they always cover their nose with their paw: this helps them conserve heat.

When they talk about where polar bears live, ice floes immediately come to mind - it is there that these predators are able to find food for themselves: seals, ringed seals, walruses, bearded seals, and other sea animals that are part of the predator’s diet live here. During the year, he travels about one and a half thousand kilometers in search of food. Thanks to the huge reserves of subcutaneous fat, he is able to not eat for quite some time. long time, but if the hunt is successful, it can easily eat up to 25 kg of meat at a time (usually a bear catches a seal once every three to four days).

Thanks to its white color, excellent hearing, perfect vision and excellent sense of smell, the bear is able to smell its prey several kilometers away (a seal at a distance of 32 km). It catches prey, sneaking up from behind shelters, or watches for it near holes: as soon as the prey sticks its head out of the water, it stuns it with its paw and pulls it out. But for some reason, polar bears hunt on the shore very rarely.

Sometimes, when he swims up to an ice floe where seals are resting, he capsizes it and catches prey in the water (it is these animals that mainly make up his diet). But a polar bear can cope with a heavier and stronger walrus only on solid ground, where it becomes clumsy.

It is interesting that the polar bear does not eat its entire prey, but only the fat and skin, everything else only if it is very hungry (polar foxes, arctic foxes, and seagulls eat the carcass after it). If there is no usual food, the polar bear feeds on carrion and does not hesitate to eat dead fish, eggs, chicks and even algae. After a meal, a polar bear spends at least twenty minutes cleaning itself, otherwise the wool will reduce its thermal insulation properties.

Thanks to this method of feeding, the polar predator receives a sufficient amount of vitamin A from its prey, which is deposited in its liver in such quantities that more than one case of liver poisoning of this animal has been recorded.

Polar bear camouflage

Polar bears are capable of perfect camouflage, and they are able to become invisible not only to their prey, but even to the infrared cameras with which scientists monitor predators. This was discovered by zoologists during a flight over the Arctic, which was made with the aim of counting the population of these animals. The equipment failed to notice the bears, since they completely merged with the surrounding ice. Even infrared cameras could not detect them: only eyes, black noses and breathing were reflected.

Bears have become invisible due to the fact that with the help of infrared cameras it is possible to see not only temperature indicators of the surface, but also the radiation that comes from the observed objects. In the case of polar bears, it turned out that their fur had radio-emitting properties similar to those of snow, which is why cameras were unable to record the animals.

Offspring

A she-bear gives birth for the first time no earlier than four years of age (and sometimes the first birth occurs at eight). She gives birth to no more than three cubs every two to three years. The mating season usually lasts from March to June, with one female followed by about three to four males, who constantly fight with each other, and adults can even attack and kill cubs. Polar bears can interbreed with brown bears, resulting in offspring that, unlike many other animal species, are also capable of reproducing.

The female bears prepare to give birth in October, starting to dig dens near the coast in the snow drifts. To do this, females often gather in one place; for example, about two hundred dens appear annually on Wrangel Island. They do not settle in them immediately, but in mid-November, and hibernate until April. Pregnancy lasts up to 250 days and the cubs appear blind and deaf, usually in the middle or end of the Arctic winter (their eyes open after a month).

Despite the impressive size of an adult, newly born babies are not much longer than a rat, and their weight ranges from 450 to 750 grams. When the cubs are about three months old and gain weight, they begin to gradually leave the den with the mother bear, gradually switching to a wandering lifestyle. The cubs live with their mother for three years, and until they are one and a half years old, she feeds them with milk, while at the same time feeding them seal blubber. The mortality rate among babies is quite high and ranges from 10 to 30%.

Animal life in the modern world

Polar bears are listed in the IUCN Red List: despite the fact that their numbers are considered stable and even growing, the slow reproduction of white predators, poaching (about 200 animals are killed annually) and high mortality among cubs make the population easily vulnerable, and in some places they have disappeared at all.

IN Lately On the territory of Russia, a sharp decrease in population has been recorded: animals living in the region of Yakutia and Chukotka have completely disappeared in some areas. The lifespan of these predators in nature is about 25 years, while in captivity they can live up to forty-five.

In addition to poachers, the lives of polar bears are affected by global warming: over the last century, air temperatures in the Arctic have risen by five degrees Celsius, which is why the area of ​​glaciers on which these animals actually live is constantly decreasing. This directly affects the population of seals, which are their main food, allowing them to accumulate the necessary fat reserves.

During melting, the ice becomes unstable, as a result of which the bears are forced to go to the coast, where there is not enough food for them, and they significantly lose weight, which negatively affects future cubs.

Another important problem is oil, which is present in considerable quantities in the sea water around drilling rigs. While thick fur protects bears from dampness and cold, if it becomes stained with oil, it loses its ability to retain air, causing the insulating effect to disappear.

As a result, the animal cools down faster, and the black skin of the polar bear runs the risk of overheating. If a predator also drinks such water or simply licks it off the fur, this will lead to kidney damage and other diseases of the gastrointestinal tract.

The predatory mammal polar bear, or polar bear (Ursus maritimus) is a close relative of the brown bear and the largest land predator on the planet today.

Characteristics and description

The polar bear is one of the largest terrestrial representatives of mammals from the order of predatory animals.. The body length of an adult individual is three meters and weighs up to a ton. The average weight of a male, as a rule, varies between 400-800 kg with a body length of 2.0-2.5 m. The height at the withers does not exceed one and a half meters. Females are much smaller, and their weight rarely exceeds 200-250 kg. The category of the smallest polar bears includes individuals inhabiting Spitsbergen, and the largest specimens are found near the Bering Sea.

This is interesting! A characteristic feature of polar bears is the presence of a fairly long neck and a flat head. The skin is black, and the color of the fur coat can vary from white to yellowish shades. In summer, the animal's fur turns yellow as a result of prolonged exposure to sunlight.

The fur of polar bears is completely devoid of pigmentation, and the hairs have a hollow structure. A feature of translucent hairs is the ability to transmit only ultraviolet light, which gives the wool high thermal insulation characteristics. There is also fur on the soles of the limbs to prevent slipping. Between the fingers there is a swimming membrane. Large claws allow the predator to hold even very strong and large prey.

Extinct subspecies

A closely related subspecies to the well-known and fairly common polar bear today is the extinct giant polar bear or U. maritimus tyrannus. A distinctive feature of this subspecies was its significantly larger body size. The body length of an adult individual could be four meters, and the average weight exceeded a ton.

On the territory of Great Britain, in Pleistocene deposits, it was possible to discover the remains of a single ulna belonging to a giant polar bear, which made it possible to determine its intermediate position. Apparently, the large predator was perfectly adapted to hunting fairly large mammals. According to scientists, the most likely reason for the extinction of the subspecies was an insufficient amount of food at the end of the glaciation period.

Habitat

The circumpolar habitat of the polar bear is limited by the territory north coast continents and the southern part of the distribution of floating ice, as well as the border of the northern warm currents of the sea. The distribution area includes four areas:

• permanent habitat;
• habitat of high animal numbers;
• place of regular residence of pregnant females;
• territory of distant calls to the south.

Polar bears inhabit the entire coast of Greenland, the ice of the Greenland Sea south to the islands of Jan Mayen, the island of Spitsbergen, as well as Franz Josef Land and Novaya Zemlya in the Barents Sea, the islands of Bear, Vaigach and Kolguev, and the Kara Sea. A significant number of polar bears are observed on the coast of the continents of the Laptev Sea, as well as the East Siberian, Chukchi and Beaufort Seas. The main habitat of the highest possible abundance of the predator is represented by the continental slope of the Arctic Ocean.

Pregnant female polar bears regularly den in the following areas:

• northwest and northeast Greenland;
• southeastern part of Spitsbergen;
• western part of Franz Josef Land;
• the northern part of the island of Novaya Zemlya;
• small islands of the Kara Sea;
• Severnaya Zemlya;
• northern and northeastern coast of the Taimyr Peninsula;
• the Lena delta and the Bear Islands of Eastern Siberia;
• coast and adjacent islands of the Chukotka Peninsula;
• Wrangel Island;
• southern Banks Island;
• Simpson Peninsula coast;
• northeastern coast of Baffin Island and Southampton Island.

Dens with pregnant polar bears have also been observed on pack ice in the Beaufort Sea. From time to time, usually in early spring, polar bears make long trips towards Iceland and Scandinavia, as well as the Kanin Peninsula, the Anadyr Bay and Kamchatka. With ice and when crossing Kamchatka, predatory animals sometimes end up in the Sea of ​​Japan and Okhotsk.

Nutritional Features

Polar bears have a very well developed sense of smell, as well as hearing and vision, so it is not difficult for a predator to notice its prey at a distance of several kilometers.

The diet of a polar bear is determined by the characteristics of its distribution area and the characteristics of its body. The predator is ideally adapted to the harsh polar winter and long swims in icy water, so its prey is most often marine representatives of the animal world, including sea ​​urchin and walruses. Eggs, chicks, young animals, as well as carrion in the form of corpses of sea animals and fish that are washed up on the coast are also used for food.

If possible, the polar bear's diet can be very selective. In captured seals or walruses, the predator primarily eats the skin and fat layer. However, a very hungry beast is capable of eating the corpses of its fellows. It is relatively rare for large predators to enrich their diet with berries and moss. Change climatic conditions had a significant impact on nutrition, so recently polar bears are increasingly hunting on land.

Lifestyle

Polar bears make seasonal migrations, which are caused by annual changes in territories and borders polar ice. In summer, animals retreat towards the pole, and in winter, the animal population moves to the southern part and enters the mainland.

This is interesting! Despite the fact that polar bears mainly stay on the coast or ice, in winter period animals lie in dens located on the mainland or island, sometimes at a distance of fifty meters from the sea line.

Duration hibernation Polar bear life usually varies between 50-80 days, but hibernates, most often pregnant females. Males and young animals are characterized by irregular and fairly short winter hibernation.

On land, this predator is fast, and also swims well and dives very well.

Despite the apparent slowness, the slowness of the polar bear is deceptive. On land, this predator is distinguished by its agility and speed, and among other things, the large animal swims well and dives very well. To protect the polar bear's body, it has very thick and dense fur, which prevents it from getting wet in icy water and has excellent heat-retaining properties. One of the most important adaptive characteristics is the presence of a massive layer of subcutaneous fat, the thickness of which can reach 8-10 cm. The white color of the coat helps the predator to successfully camouflage itself against the background of snow and ice..

Reproduction

Based on numerous observations, the rutting period for polar bears lasts about a month and usually begins in mid-March. At this time, predators are divided into pairs, but there are also females accompanied by several males at once. The mating period lasts a couple of weeks.

Polar bear pregnancy

Lasts approximately eight months, but depending on a number of conditions, can vary between 195-262 days. It is almost impossible to visually distinguish a pregnant female from an unmarried polar bear. About a couple of months before giving birth, behavioral differences appear and females become irritable, inactive, lie on their stomachs for a long time and lose their appetite. A litter often contains a pair of cubs, and the birth of one cub is typical for young, primiparous females. A pregnant bear comes to land in the fall, and spends the entire winter period in a snowy den, most often located near the sea coast.

Caring for cubs

In the first days after birth, polar bear lies curled up on its side almost all the time. Short and sparse hair is not sufficient for independent heating, so newborn cubs are located between the mother’s paws and her chest, and the polar bear warms them with her breath. The average weight of newborn cubs most often does not exceed a kilogram with a body length of a quarter of a meter.

The cubs are born blind, and only at the age of five weeks do they open their eyes. A mother bear feeds her month-old cubs while sitting. The mass emergence of female bears occurs in March. Through a hole dug outside, the bear begins to gradually take her cubs out for a walk, but with the onset of night the animals return to the den again. During walks, the cubs play and dig in the snow.

This is interesting! In the polar bear population, approximately 15-29% of cubs and about 4-15% of immature individuals die.

Enemies in nature

IN natural conditions polar bears, due to their size and predatory instinct, have practically no enemies. The death of polar bears is most often caused by accidental injuries as a result of intraspecific clashes or when hunting walruses that are too large. Orca whales and polar sharks also pose a certain danger to adults and young individuals. Most often bears die from starvation.

Man was the most terrible enemy of the polar bear, and such peoples of the North as the Chukchi, Nenets and Eskimos hunted this polar predator from time immemorial. Fishing operations that began in the second half of the last century became disastrous for the population. During one season, St. John's worts destroyed more than a hundred individuals. More than sixty years ago, polar bear hunting was closed, and since 1965 it has been included in the Red Book.

Danger to humans

Cases of polar bear attacks on people are well known, and the most striking evidence of the predator’s aggression is recorded in the notes and reports of polar travelers, so you need to move around in places where a polar bear may appear, you need to be extremely careful. In the territory settlements, located near the habitat of the polar predator, all containers with household waste must be inaccessible to the hungry animal. In the cities of the Canadian province, so-called “prisons” have been specially created in which bears approaching the city limits are temporarily kept.

The polar bear is the world's largest terrestrial carnivore, living in the Arctic: in the remote northern regions of Greenland, Norway, Canada, and Russia.

And although northern bears traditionally look white, surprisingly, their fur lacks white pigment, in fact it is translucent, and its skin is black. So why is the polar bear white? The answer to this question is provided by scientists' research into what the polar bear's fur is made of, as well as the study of optical phenomena that affect the color of this animal's fur.

Interesting fact: The polar bear is the largest land predator on Earth. The length of the animal is about 3 meters, weight – up to 1 ton.

What is polar bear fur made of?

The polar bear's fur contains two layers of hairs: an outer protective layer consisting of long (5-15 cm) guard hairs; and a dense insulating undercoat, the hairs of which are shorter and finer than those in the protective layer.

The polar bear's skin is black and its fur is translucent.

Properties of protective hairs:

• translucent;
• hollow, i.e. empty inside;
• rough, narrowed (gradually reaching the base);
• contain particles that scatter light;
• contain salt particles;
• consist of the protein “keratin”.

The translucent hairs of the bear's fur also appear white due to the thickness of the animal's fur.

Influence of optical phenomena

The fur of the northern bear is translucent, but due to the properties of the protective hairs that are involved in the creation optical effect, these animal fur appears white. From an optical point of view, the reason why a polar bear appears white is due to the effect of light on the animal's hair.

Luminescence

Exposure to light causes a reaction known as luminescence

When the sun's rays fall on a polar bear's fur, some of this light gets trapped in the fur. This light energy is reflected inside the hollow part of the hairs, causing a reaction that is the emission of light - luminescence. This happens every time a beam of light comes into contact with an animal's fur.

Luminescence is accelerated by light-scattering particles in the hairs, which destroy the light beam. When light hits a light-scattering particle, it splits into more rays that move in different directions. Light scattering particles are found both on the inner surface of the hairs and on the outer surface. The scattering of light causes more white color to appear and be further emitted by the animal's hair. Thus, the bear's translucent fur reflects sunlight. This is the reason why polar bears are especially bright in direct sunlight. The brighter the lighting, the more light is reflected by the polar bear's translucent fur.

Salt particles

Sea salt particles

Polar bears spend a lot of time in water, which is why Latin name these representatives of the bear family ursus maritimus, which means “sea bear”. Polar bears collect salt particles while swimming or staying near salty sea water. Salt particles along the rough surface of the wool also act as light scattering particles, which increase the number of light rays and enhance luminescence.

Ultraviolet light

Ultraviolet light in the optical spectrum

When the sun shines on a polar bear, ultraviolet light travels along the guard hairs to their base and penetrates the animal's dark skin. When ultraviolet light hits the skin, it causes a whitish color due to fluorescence (the ability to release absorbed energy as cool light radiation). Fluorescence is a type of luminescence. Thus, ultraviolet radiation also causes the bear's fur to turn white.

Interesting fact: Ultraviolet rays, which are transmitted through translucent hairs, give the polar bear's fur its insulating properties.

Keratin

Keratin is a common natural protein found in skin, nails and hair. Similar to humans, bear hairs contain keratin. The protein molecules of keratin give off a whitish color, which further contributes to the appearance of white fur in the bear.

Why does a polar bear change color?

Now that we know why polar bears are white, it's interesting to know why some of them have yellow, brownish, and even green hues in their fur.

In warm climates, polar bears turn green as algae colonize the interior of their fur.

With changes in the seasons, habitat, and fur that grows throughout the year, slight differences in the color of the polar bear's fur are noticeable, which helps it adapt to environment. In late fall and winter, when polar bears shed their fur and grow new fur, they appear whiter than in summer, when the fur turns yellowish due to wear and constant exposure to the sun. Bears that live on ice away from water appear whiter than bears that swim a lot. Polar bears on land where there is little or no snow wear light brown fur.

The fur of polar bears that live in warm conditions (for example, in zoos) sometimes takes on a green tint. This happens because algae growing in bodies of water colonize the internal environment of the bear's hollow hairs and reflect green color. In the cold Arctic north, algae do not grow, so the polar bears that live in the Arctic remain white. This helps them camouflage themselves when hunting, blending into the snow-white Arctic atmosphere.

Polar bears in the Arctic remain white

Polar bears are amazing animals that are even color-adapted to their Arctic home.

Having black skin and translucent fur, the polar bear appears white due to the structure and properties of the hairs, which have free space inside, and the light that penetrates them and creates luminescence. The white color of the bear's translucent fur is also given by ultraviolet light, which causes fluorescence, and keratin, the molecules of which emit a whitish color.

Each of these elements maintains the white color of the polar bear's coat. So the polar bear's fur reflects a lot of light, which is why it is white.

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