The polar bear is the largest terrestrial carnivore in the world. Polar bears are also considered marine mammals, as they spend most of the year at sea. The scientific name of the polar bear is Ursus maritimus. The first polar bear was discovered by English Royal Navy Officer John Phipps in 1774. He suggested the scientific name Ursus maritimus for polar bears.
About Polar Bear Habitat
Polar bears are found in the coldest places in the northern part of the world. Polar bears live in the Arctic Ocean, Norway, Russia, Greenland, Alaska in the United States, and Canada. There are 19 subspecies of polar bear.
Polar Bear Population
Polar bears can be seen in five countries around the world. According to The International Union for the Conservation of Nature (IUCN), there are approximately 26,000 polar bears worldwide, and they are on the Vulnerable species list. But there is no exact calculation of their numbers. Because of the hostile climate in the polar regions, it is almost impossible to count their exact numbers. However, biologists estimate that the number of polar bears in the world is 22,000-31,000. Interestingly, two-thirds of all polar bears in the world live in Canada.
Adaptation of polar bears
The climate in the Arctic is different from that in other parts of the world. In winter the sun is not see here. The sunset does not go away in summer. The average winter temperature is -40 degrees Celsius. How do polar bears survive in this artick region?
The body of the polar bear has been specially adapted to survive in the ice kingdom. Before we know how polar bears adapted, we need to know how these bears came to the Arctic?
Where did polar bears come from?
Where the polar bear came from, scientists say that the polar bear is an evolutionary form of a part of the brown bear. Polar bears are the successors of brown bears. Scientists have found that the genetic makeup of polar bears and brown bears is closely related. Although polar bears and brown bears are different species, but they can interbreed. Which indicates that they came from the same ancestor.
During the Pleistocene Glacier, a group of brown bears separated from the mainland of eastern Siberia. When the brown bears spread out in search of food, a group of them separated from the main group and were trapped in the north. Huge ice and snow separated the two groups. The group of trapped brown bears begin to fight for survival. Those who have achieved some evolutionary features in the struggle for survival have survived, while others have died in severe winters.
A fossil of a polar bear was found in Prince Charles Foreland in 2004. The fossil is a jaw bone 110,000 to 130,000 years old. It is the oldest fossil of polar bears. Fossil analysis and DNA testing show that polar bears became isolated from brown bears 150000 years ago. From 10,000 to 20,000 years ago, the molar teeth of polar bears changed a lot from the teeth of brown bears. Researchers believe that polar bears have gradually acquired adaptive traits in order to survive in the icy environment. Currently polar bears are a distinct species.
Adaptive traits of polar bears
Body temperature must be maintained to survive the polar region’s cold. Polar bears have mastered this technique very well for survival. Polar bears have achieved some adaptive traits to maintain body temperature, search for food, protect themselves from predators, and survive extreme weather. Some adaptive features of polar bears are as follows-
01. Polar Bear Fur Color
There are no large trees in the arctic region. A layer of white ice all around. Although in summer the shrubs and grasses grow in the plains. It is almost impossible to hunt in secret in this white ice. So, in order to hide themselves behind the ice, the color of the polar bear’s fur has become clear and transparent, which looks white in our eyes. Due to their white color, they can easily hide and hunt their prey. They can also hide themselves from predators because of their white color.
02. Polar Bear Fur Structure
The whole body of polar bear is covered with fur to protect against cold, except nos and the foot pad. Polar bear fur has two layers of coat. Fur, oily and waterproof. The inner layer is the undercoat, which is small and thick. The outer layer is guard hair, which is long up to 5-15 cm in length. The fur of polar bears grows about half an inch per month. The coat’s outer layer helps the bear hold air close to its skin, which helps regulate body temperature. The inner layer protects the body from snowfall. As they have two layers of fur, they can retain more sun heat. This keeps their bodies warm. As the fur is water-resistant, their body does not get cold even if they are in water.
03. Polar Bear Skin Color
The skin color of polar bears is black. Although the skin color of other bears is pink. Black skin is another distinguishing feature of the polar bear. Their skin has evolved to maintain body temperature and retain heat from the sun during severe winters. Black skin helps absorb sunlight. Due to the black skin, the absorbed heat cannot come out from the body.
04. Polar Bear Fat Layer
The polar bear has a four-inch-thick layer of fat. The fat layer keeps their body temperature. These fats provide energy in case of a food crisis. The fat layer also helps the mother bear survive without food for several months during the breeding season. The fat layer acts as a thermal insulator. It also helps the polar bear to stay afloat in the water.
05. Anatomical traits of polar bears
The polar bear’s ears, legs and tails are short. The tails are about 7-8 inches long. The small tails, ear and legs help them maintain balance and temperature on the ice. Polar bears have powerful paws. The paws of polar bears are relatively large and flexible. Because of its large size, it can carry body weight and can walk easily on slippery ice and snow due to its flexibility. The claws of polar bears are smaller than brown bears, but stronger. Their legs are short but very strong. With strong legs, they can easily break the ice and hunt seals. They Can swim fast with wide paws.
The head and mouth of the polar bear are narrow and long. The body parts are enormous. The main reason for the narrowing of the mouth and head is to catch their main prey seal from the ice hole. As the front part is narrow, it can easily enter the seal hole and bite on the seal. The body parts are so strong that they can easily pull out the massive seal from the nest. The polar bear has 42 strong teeth in its mouth. Mouth teeth are smaller than brown bears.
06. The polar bear’s sense of smell
The polar bear’s sense of smell is nicely adapted. Polar bears’ sense of smell is one of the most advanced adaptive traits. Polar bears can detect prey from 1.5 miles (2.41 km) away. They can also detect seals under 3 feet of ice.
07. Polar Bear’s are Good Swimmers
Like other mammals, polar bears are natural swimmers. They can swim at a speed of ten kilometers per hour. Polar bears can swim up to three minutes underwater to catch prey.
08. Dietary adaptation
One of the adaptation traits of the polar region is the presence of fat in the diet of polar bears. The main food of polar bears is fatty seals and marine fish. These high-fat foods increase the amount of fat in polar bears. Which helps them survive in the polar region.
The social structure of polar bears
Polar bears are quiet and solitary animals. They do not live in groups. Unlike other bears, polar bears do not show regionalism. If there is a problem in one area or there is more competition, they move to another area. As a result, the distance between two polar bears is much greater.
During the breeding season, male and female polar bears may stay together for several days. That’s the time they play, hug, and sleep together. Many times, more than one male has to fight for a mate during reproduction.
Sometimes multiple polar bears are seen hugging each other and sleeping. It is a kind of interaction. In this way, both bears get warm. Although the polar bears are far from each other, they have a familiar relationship. When a male bear approaches a female bear, they develop a friendly relationship. Even if they meet again after a long time, they will show the previous friendly relationship.
Most of the time, mother polar bears give birth to two cubs at once. The cubs like to play together. They like to fight with each other. After the birth of the child, the female polar bear takes care of the cubs. The cubs stay with the mother until they reach adulthood.
After weaning, when the cubs are full, the mother bear releases them. Then the cubs stay together for a few days. During this time, they hunt, eat and play together. After a few days, they became separated.
Polar bears release pheromones to maintain contact with each other in the vast polar region. Polar bears can communicate with each other with different sounds or respond to calls. Baby polar bears communicate with each other with a kind of sound.
The ancestral brown bear is fierce but the polar bear is calm. They do not attack people unless they are absolutely compelled. Although the presence of people in the polar regions is very low. Even then, attacks on humans by polar bears are rare. Where people are regularly attacked by brown bears.
Diet Of Polar Bear
The polar bear is called Hypercarnivore. Hypercarnivore animals need 70% of meat in their diet. Among the bear species, polar bears are the most dependent on meat. Polar bears’ main and favorite food is ring seal and bearded seal.
These two types of seals are abundant in the polar region. When seals come out of an ice hole to breathe, rest, or sunbathe, they are preyed by polar bears.
Ring seals and bearded seals are small, so polar bears can easily prey on them. Also on the list of polar bear food are Fourhorn Sculpin, Arctic char, Harp seal, Harbor Seal, Hooded Seal, Beluga Whales, Narwhals.
The leading food of polar bears is sea seals and various kinds of fish. Global warming has begun to melt the ice. In lack of ice, seal hunting is also challenging for polar bears. So polar bears have changed their diet habits. This list includes mammals like Muskox, Reindeer, and their calves. Also, Arctic birds, rodents, crabs, shrimps, various kinds of small fish, eggs, grasses, shrubs, leaves, and roots. If there is a food crisis, they also prey on their own species of polar bears.
Polar bears catch and eat prey throughout the year. However, the presence of prey is less when the snow melts in late summer and early autumn. At this time, they may survive several months without any food. They pass these times with the help of stored fat in the body. This does not happen regularly. They do this whenever there is a shortage of food.
Polar bear Hunting Techniques
It is challenging to catch a seal from the water. Polar bears cannot hunt seals directly from the water unless absolutely compelled. They wait in front of Seal’s hole to hunt. As soon as the seals come out, they attack the seals and break the seal’s skull.
The polar bear’s sense of smell is much improved. They can find seal nests by the smell of seals breathing. After finding the seal’s nest, they enter the seal’s nest with their narrow mouths and pull out the seal.
Another hunting method is to hide behind the prey and move to the prey. Especially when the seals rest on the ice for a sunbath, the polar bear scrolls and comes within 10-12 feet. Then they quickly attacked the prey and broke the skull of the prey. The mother seals build a nest in the ice to give birth. These are also called birth layers. The polar bear breaks this layer with its strong legs and hunts seals.
Reproduction of Polar Bear
The female polar bear is suitable for breeding at the age of four to five years. Male polar bears reach sexual maturity at the age of six. During pregnancy, the female polar bear does not eat for about eight months. During this time, they maintain the required energy flow with the help of fat accumulated in their body. So many female polar bears do not conceive even if they are five years old because of the lack of required body fat and weight. Again, for a female, there is a competition between multiple male polar bears. So, even though they reach sexual maturity at the age of six, male polar bears do not breed before eight to ten years.
Polar bears are solitary animals. During the breeding season, the male polar bear follows the truck of the female polar bear. A male polar bear can follow a female polar bear truck from a distance of 100 km.
Most female polar bears give birth once every three years.
In April and May, males and females mate. The female polar bear is polygamous. This means that a female polar bear mates with more than one male polar bear during reproduction. Multiple male polar bears fight each other for mating. Sometimes this fight becomes deadly. The winning male mates with the female polar bear, and they spend a couple of days together.
After mating, the fertilized egg stays in a free-floating state for four months. Fertilized eggs do not develop during this time. The reason for the delay is choosing the right time to give birth and acquiring the necessary strength for the body of the mother bear.
During these four months, the mother bear doubles the amount of food. Because in order to give birth to cubs, a lot of fat has to be stored in the body, and weight has to be increased by 200 kg.
The gestation period is about eight months, including the delay of fertilized eggs. However, the gestation period is four months from the actual development of the fetus.
Life Cycle of Polar Bears
Some female polar bears build maternity dens on the ice of the sea. Most polar bears build their maternity dens in the land ice. This maternity den has two to three chambers. The mother bear enters the maternity den before the cubs are born. A hole is made in the dens for ventilation through the chamber’s ceiling. The maternity dens protect the cubs from the harshness of winter. Due to the body temperature of the polar bear, the temperature inside the dens is much higher than the outside temperature.
Between November and February, mother bears give birth. Two cubs are born per litter. Sometimes, one or three cubs can be born. However, the birth of four cubs at the same time is very rare.
Babies are born blind. At birth, the cubs may weigh one kilogram or less. After birth, the mother polar bear stays in the maternity dens with her cubs from February to mid-April. At this time, the mother polar bear does not take any food. It burns body fat and absorbs energy. Cubs are breastfed. The female polar bear has four mammalian glands. It can easily feed cubs sitting or lying down. Cubs gain weight quickly because of the high fat content in their mother’s breast milk. Polar bear milk contains 33% fat.
Within a month of birth, the cubs’ eyes open. The first few months after birth, cubs stay in the mother’s warm womb. During this time, they spend most of the time breastfeeding and sleeping. At two months of age, cubs begin to walk in the den. During this time, fur and teeth are grown.
In mid-April, the mother bear gets out of the maternity den with her cubs. At this time, cubs weigh about 10-15 kg. The mothers and cubs spend 10-12 days near the dens. During this time, the cubs play around the dens. The mother eats the grass and plants of the surrounding land. 10-12 days later, when the cubs have achieved the technique of adapting to the outside environment, the mother polar bear begins to walk with the cubs to the sea, where their favorite food seals are present.
When the cubs are three to four months old, the mother bear feeds the cubs six times a day. As the cubs grow older, the amount of nursing decreases. This time they started eating seals with mom. At the same time, the cubs grow faster by combining breast milk fat and seal fat. At the age of eight months, they gained 45 kg.
The cubs stays with the mother for two and a half years. During this time, they mastered the techniques of catching prey. At the age of two and a half years, the mother chases her cubs away or the cubs leave. The Mom bear bear prepares for reproduction again.
The lifespan of polar bears
The average lifespan of a polar bear in a wild environment is 25-30 years. Polar bears survive more years in captivity. A female polar bear has a record of surviving up to 43 years in captivity.
There is no accurate information on the cause of death of wild polar bears. It is thought that as they grow older, they lose their ability to catch prey and die due to lack of food. Someone dies while fighting during the breeding season. Some also die in natural disasters.
Polar bear hunters
Although polar bears are the largest predators in the Arctic, they are also attacked by other animals. Polar foxes often prey on bear cubs. Polar bear cubs are also preyed upon by sharks, wolves, and brown bears.
Humans are the biggest predators of adult polar bears. Humans hunt polar bears with the help of dogs and kill them with spears or bullets.
People hunt polar bears for meat, skin and fur. Precious winter clothing is made from polar bear skin. Skin and fur are also used to make carpets and other utensils. Amulets and ornaments are made from polar bear teeth. Polar bear’s fat is used for fuel. Dried heart and gall bladder are used for medicine. Basically, people hunt polar bears for these commercial purposes.
Global warming is causing a polar bear habitat crisis. Their numbers are also declining due to killings by humans. Speaking of hope, The five countries where polar bears are found are currently taking effective measures to save polar bears.