Polar Bear Facts

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  • How Much Does a Polar Bear Weigh? – Polar Bear Weight

    Polar bear weight varies with the season because of the availability of food sources. The adult males are generally heavier than adult females. Ursus maritimus are sexually dimorphic in fact one of the most dimorphic mammals in the marine world. Polar bear cubs weigh less than a kilogram but male cubs are greater than female cubs even at birth. Now let us study how much do polar bears weigh? 

    How Much Does a Polar Bear Weigh? – Polar Bear Weight

    A full grown polar bear weighs as much as 350–700 kg (772–1,543 lb) but the average weight measure around 385 to 410 kg (849 to 904 lb). Males attain this much weight when they are 10 years of age. Kodiak bears are slightly heavier than adult white bears.

    In the Beaufort Sea, males average 450 kg (992 lb) on maturity. They are nearly twice the weight of females. The heaviest male polar bear ever recorded was 1,002 kg (2,209 lb). The bear was shot in northern Alaska (Kotzebue Sound) in 1960.

    Read More: How Big is a Male Polar Bear?

    how much does a polar bear weigh?
    A mother bear is followed by her cubs. How much do polar bears weigh? Photo by: GUDKOV ANDREY/Shutterstock

    How Much Does a Female Polar Bear Weigh?

    The weight of an adult female is one half of the male’s body mass. Females weigh around 150– 250 kg (331–551 lb).The maximum reported weight in females is 260 kg (573 lb) but it is extremely rare. During pregnancy adult females put on too much weight almost equal to adult males’ mass. Females gain as much as 500 kg (1,102 lb) weight when they are pregnant.

    During pregnancy adult females put on too much weight almost equal to adult males’ mass. Females gain as much as 500 kg (1,102 lb) weight when they are pregnant.

    Females attain sexual maturity at 6 years of age. Soon after age they will put on much weight because of pregnancy. Extra weight is not because of cubs but due to the extra fats which she stored. She must store excess fats in order to spend days in the without eating. The female will come out of den in the spring season.

    How Much Does a Polar Bear Cub Weigh?

    Main Article: How Much Does a Baby Polar Bear Weigh?

    The polar bear cubs weigh 1 – 1.5 pounds (0.8 kilograms) at birth. Females are smaller and less heavy than males at birth. When the cubs reach 90 – 100 days age they leave the den. At this time they weigh up to 33 pounds (115 kg). A cub born in the Alaskan zoo averages 18 pounds (8 kg) and the bear was 90 days old.

    How Many Pounds Does a Polar Bear Weigh?

    Polar bears weigh around 772 to 1,543 pounds but most bears weigh less than 1,000 pounds. The heaviest polar bear ever recorded at the Guinness Book of World Records measured at 849 to 904 pounds. The average weight of a female polar bear in pounds is about 573 pounds.

    How Much Does a Polar Bear Weigh? – Video

  • Polar Bear vs Walrus

    While polar bear (Ursus maritimus) is a land-based marine mammal the walrus (Odobenus rosmarus) is a flippered aquatic mammal. The walrus is recognized by its prominent tusks like elephants’. White bears are the predators of walruses. However walrus is a big animal and only adult bears can afford to take down such a large prey. Sometimes young polar bears also get killed by the walrus.

    Polar Bear vs Walrus

    Adult walruses typically measure 2,000 kg (4,400 lb) in weight whereas male polar bears can weigh as much as 350 – 700 kilograms. The weight of the heaviest polar bear is reported at 1,000 kg. Clearly there is a significant difference in sizes of both marine animals. The biggest walrus is twice the size of the biggest polar bear. Despite the size difference polar bear preys on walrus and not the other way round.

    Where Do Polar Bears and Walruses Live?

    Polar bears and the walrus live in the Northern Hemisphere. They both have occupied much of the arctic including Atlantic Ocean.

    Polar Bear vs Walrus Hunting

    While polar bears have long been the victim by the indigenous people walrus isn’t safe either. Indigenous people kill walrus not only for its unique tusks but also for skin, meat, bone, and fat. In the 19th and 20th century people used walrus ivory and blubber to serve numerous purposes.

    Polar Bear vs Walrus Diet

    Unlike polar bears walruses have quite diverse diet. Walrus is thought to consume 60 genera of aquatic animals. Walrus eats shrimps, crabs, sea cucumbers, mollusks and many others. Both polar bears and walruses prey on ringed seals.

    Polar Bear vs Walrus Life history

    Walrus and polar bear seem to have a similar lifespan. Polar bears live around 15 – 25 years and walrus’ lifespan ranges from 20 – 30 years.

    Walrus attains the sexual maturity at 15 years age whereas polar bears become mature as early as in 4 – 5 years.

    Female polar bears and female walruses are called sow.

    Polar bear cub weighs only one kilogram at birth as against the walrus cub that weighs as much as 45 to 75 kg.

    While polar bears live alone, walrus breeds in colonies of tens of thousands of individuals.

    Population

    The overall global population of walrus is estimated at 200,000. Polar bears have a total population of about 25,000.

    Predators

    Polar bears have no natural predator in the arctic. Walrus has two potential predators; one is polar bear and the other is a killer whale.

  • Polar Bear vs Grizzly Bear | Polar Bear vs Brown Bear

    Polar bear (Ursus maritimus) and grizzly bear (Ursos arctos) are not only the largest terrestrial carnivorans, they are close cousins too. Polar bear is the largest whereas brown bear is the second largest terrestrial mammal living today. They both resemble in size and strength. Grizzly bears and polar bears are super powerful. They possess the amazing ability to take down prey nearly the size of their own. Grizzlies are also called North American brown bear and scientists never use the word grizzly for brown bears.

    While there is virtually no chance that brown bear would meet polar bear people often get confused as to who would win polar bear vs grizzly bear fight.

    Polar Bear vs Grizzly Bear Evolution

    The brown bear seems to have evolved from the Asian subspecies Ursus savini about 800,000 years ago. The oldest fossil discovered in China and it is 500,000 years old. Grizzlies are thought to have occupied the Europe around 250,000 years ago.

    Polar bears separated from other carnivorans around 38 million years ago. The oldest fossil discovered in Prince Charles Foreland in 2004 and it is 130,000 – 110,000 years old. The study of fossils suggests that the polar bear’s molar teeth changed drastically from brown bear’s teeth around 10,000 – 20,000 years ago. Before that brown bear and polar bears had the same molar teeth.

    Both polar bears and grizzly bears are genetically same species—DNA proves it. They diverged from one another about 400,000 years ago. Even today in captivity polar and brown bear can mate successfully giving rise to pizzly or groalar bear.

    Who would Win Polar Bear vs Grizzly Bear | Polar Bear vs Grizzly Bear Fight

    It is reasonable to assume that the virtual match between polar bears and grizzly bear would be quite tough because both are extremely muscular and massive in their body size. While brown bears possess longer claws polar bears have got elongated skull with long canines that can rip off the flesh. The comparison is surely a tough one since both animals are absolutely compatible in their physical characteristics.

    Read More: Is a Polar Bear Bigger than a Grizzly Bear?

    Grizzly is more aggressive animal as compared to the polar bears. Polar bears usually avoid fighting and they can even walk away if they see humans but grizzlies will charge against any possible intruder.

    Polar Bear vs Grizzly Bear Size

    Head-and-body Length

    • The overall length of grizzly bear is about 1.4 to 2.8 m (4 ft 7 in to 9 ft 2 in) and it stands 70 to 153 cm (2 ft 4 in to 5 ft 0 in) at the shoulder.
    • Polar bears measures around 2.4–3 meters (7 ft 10 in–9 ft 10 in) in total length and the shoulder height is estimated at 122 to 160 cm (4 ft 0 in to 5 ft 3 in).

    Tail Length

    • Grizzly bears have relatively longer tail than polar bears.
    • The brown bear’s tail measures around 6 to 22 cm (2.4 to 8.7 in) whereas the polar bear’s tail is the shortest of all bear species measuring 7 to 13 cm (2.8 to 5.1 in) in total length.

    Physical Features

    • The polar bear’s body is rather elongated as compared to that of brown bears. The nose and skull are also longer in white bears and shorter in brown bears.
    • Brown bears seem to possess larger ears and legs than polar bear’s.
    • Brown bears also possess longer and sharper claws as compared to their cousins. The polar bear’s claws are used provide a firm grip while walking on the sea ice whereas grizzly bear’s claws are mainly used for digging and killing prey.
    • Polar bears are remarkable swimmers and they are known to swim for days without stopping. Brown bears lack such ability.

    Read More: Polar Bear vs Siberian Tiger

    polar bear vs grizzly bearPolar Bear vs Grizzly Bear Habitat

    • Grizzlies are thought to make homes in a wide variety of habitats such as temperate forests, open or semi-open landscapes, coastal estuaries, steppes, meadows, alpine forests, and desert edges. They have the most diverse habitat ranges of all bear species.
    • The essential characteristics of a polar bear’s habitat are sea ice and water. The reason is that the bear hunts seals on ice floes.

    Polar Bear vs Grizzly Bear Behavior

    • Like polar bears grizzlies can also stand on their hind legs. In fact brown bears can also walk a bit but polar bears can’t.
    • Both species are crepuscular but grizzlies mostly show nocturnal behavior as they prefer to come out at dusk.
    • Grizzlies have a home range of about 115 km2 (44 sq mi). Polar bears have remote ranges.
    • Polar bears are not territorial but brown bears actively defend their territories.
    • In both species males do not take part in raising the cubs.
    • The typical lifespan of brown bears is about 25 years with one captive individual died at the age of 50 years. Polar bears have also the same average life expectancy.
    • Grizzlies are omnivorous while polar bears are exclusively carnivores. Grizzly bear eats salmon, sedges, forbs, plants, shoots, grasses, and carrion. Polar bears feed on ringed and bearded seals.

  • Polar Bear Teeth – Do Polar Bears have Sharp Teeth?

    Scientists weren’t able to explain history of polar bear’s teeth until in 2004 when they discovered 130,000 – 110,000-year-old polar bear jaw bone. This was the oldest jaw bone and its discovery answered many questions and solved numerous puzzles on the skull anatomy of a polar bear. The fossil was found on Prince Charles Foreland. Fossil studies suggest that the polar bear’s molar teeth transformed into a new form around 10,000 – 20,000 years ago and the shape was entirely different from those of brown bear’s teeth. Before that time polar bears and brown bears shared similar teeth characteristics. The arctic bears separated from their brown cousins during the Pleistocene period probably in the eastern Siberia.

    Polar Bears possess typical carnivorous heterodont dentition. Heterodont dentition explains much about the polar bear’s feeding behavior. It is an anatomical explanation of teeth which means that the animal possess more than one tooth morphology. They have teeth of different lengths and shapes. Perhaps you’d love all these interesting polar bear teeth facts.

    Polar Bear Teeth – Do Polar Bears have Sharp Teeth?

    • The polar bear’s teeth are classified into three categories namely; incisors, canines, and cheek teeth (molars and premolars). While larger teeth such as incisors and canines are fixed rostrally the molars and premolars are set caudally inside the mouth.
    • There is a long gap between the functional canine and molariform teeth. Inside the gap lie the first premolars which are vestigial.
    • Thanks to this big gap that allows the bear to pierce into the thick bodies of seals and more importantly without facing any interference from the cheek teeth. Unlike in brown bears the cheek teeth in polar bears are significantly reduced in size and also the carnassials are more pronounced in white bears than in brown bears.
    • These carnassials truly reflect the predatory lifestyle of an arctic bear. Their teeth are perfect to grab the prey and tear it apart.
    • Brown bear’s teeth are well adapted to grinding grasses whereas polar bear’s teeth definitely serve no such purpose. While male polar bears possess larger and heavier canines than those of females the molar arcade is same in both sexes.
    • The ratio of condylobasal length to zygomatic width (L/W) is 1.59 in brown bears but in polar bears the ratio is 1.63. If we look at the canines the difference appears to be greater than the actual measurements.
    • The incisors are attached to the premaxillary bone. The premaxillary bone is attached to the upper jaw of an animal bearing teeth. However canines lie in the maxilla which is quite adjacent to premaxilla.
    • While molar teeth are flat and are mainly used in chewing, the canines, premolars, and incisors are primary or deciduous teeth. The molars grow from maxillae whereas the premolars sprout from the maxillary bones.
    • Polar bears’ teeth serve different functions and none of them resembles the other. This can truly be troublesome provided the bear loses tooth in fight. If one of the teeth is broken then it probably affects the dietary habits of a polar bear.
    • Polar bear’s primary teeth appear to replace vertically and once in a lifetime. This means that if a polar bear loses her deciduous teeth the second time then it must learn to live without deciduous teeth.

    Read More: How Much Do Polar Bears Eat?

    do polar bears have sharp teethFunctions of Polar Bear Teeth

    • Incisors are primarily used either for slicing or for chipping food. The bear can also use (pointed) incisors for cutting thick skin of a seal.
    • The cheek teeth are equally effective in that they help they facilitate in crushing and grinding the food before the molars chew it.
    • Several characteristic features of a skull make up the carnivoran adaptation of a polar bear. The powerful temporal muscles and fossae are used to rip the flesh and also for killing the prey. These muscles also play a part when the bear holds the prey temporarily. Polar bear however cannot divide the flesh inside her mouth with these muscles. The temporal muscles are only used to tear prey.
    • The polar bear’s jaw movement has a limited horizontal motion in fact they are not able to move the upper and lower jaws on sideways. They can have a smooth vertical movement though. Polar bears have shallow mandibular fossae which resembles like that of a dog. They are thought to possess much pronounced dentary as compared to other marine mammals.

    How Do Polar Bears Swallow Food?

    Read More: What Do Polar Bears Eat?

    Polar bears are more likely to swallow food than they chew. The jaw muscles act in coordination with each other to pass the food via oral cavity through the larynx. The bones of the head likely facilitate in swallowing process. The hyoid apparatus which holds the larynx in place supports the tongue is extremely significant while swallowing and feeding. Muscles that will move the hyoid apparatus up and down occur in between basihyal and tongue.

    How Many Teeth Does a Polar Bear have?

    Polar bears are arguably the most carnivorans in the bear family. The only characteristic adaptation that makes icy bears the most carnivorous is their sharp teeth. The polar bear has 42 teeth in total with the cheek teeth appear to be more pointed than in the brown bears. Besides the bear’s canines are not only sharper but also greater in size than in brown bears.

    These large canines describe the exclusive meat-eating ability of a bear more than any other teeth. Polar bears have dental formula of 3.1.4.23.1.4.3 which they share with all other Ursids.

    Polar Bear Teeth – Video

    • POLAR BEAR FEATURES: Polar bears are primarily known for their acute sense of smell. Thanks to its sharp nose with the help of which the bear is able to smell its primary prey (ringed seal) hidden 2 feet under the snow…
    • POLAR BEAR SKULL:The polar bear’s skull is a typical of any other land carnivores. Bears unlike other carnivores have relatively deep and flattened mandibular fossa. The mandibular fossa is called jaw hinge…
    • POLAR BEAR TAXONOMY: Constantine J. Phipps in 1774 was the first one to give polar bears a scientific name Ursus maritimus. Two years later Pallas came up with his scientific name Ursus marinus… 

  • Polar Bear Taxonomy

    People living in the Arctic rarely call polar bears polar bears. They will call polar bears with many different names. Prominent among the names are white bear, nanook, eisbar, nanuq, sea bear, and ice bear. Not only do the Arctic people call white bears with several names scientists also could not agree on a single scientific name.

    Polar bear taxonomy

    Constantine J. Phipps in 1774 was the first one to give polar bears a scientific name Ursus maritimus. Two years later Pallas came up with his scientific name Ursus marinus. Similarly Knotterus-Meyer (1908) suggested Thallassarctos eogroenlandicus; Shaw proposed Ursus Polaris, and Erdbrink together with Thenius described the polar bears in 1953 Ursus (Thalarctos) maritimus. This is probably due to the inbreeding that occurred between grizzlies and white bears.

    Björn Olof Lennartson Kurtén, a Finnish vertebrate paleontologist, analyzed the bear fossils in 1964 which suggested that white bears likely to have originated from brown bears. It goes back to the mid-Pleistocene period in Siberia. Kurten concluded that the overall population of polar bears represents a single species and it doesn’t matter how far they live from one another. That is to say there seems to be no subspecies of white bears. However in his later explanations and examinations of fossil evidences Kurte believed that polar bear had one subspecies that might have lived in the Pleistocene period. He suggested a name Ursus maritimus tyrannus for the subspecies and said that it was far bigger than the present-day polar bear.

    Scientists followed Kurte didn’t seem to agree with his new findings of a subspecies. Thus they promoted the name Ursus maritimus. Wilson, Manning, and Harington were amongst the chief scientists. The most recent fossils belonged to 130,000 to 110,000-year-old. It was discovered in 2004 in Charles Foreland. This was a remarkable discovery because it helped scientists to understand that polar bear molar teeth underwent major change from brown bear teeth around 10,000 – 10,000 years ago.

  • What Does a Polar Bear Sound Like? – Polar Bear Sounds

    Polar bears have a range of vocalizations but they are no noisy animals. Icy bears remain quiet and live solitary lives most of the time. However polar bears’ sounds are heard either during mating season when males attempt to convince its mating partner or when the individuals fight each other.

    Mature male bears produce sounds in order to show aggression either before the fight or during fighting. Prominent among the aggressive sounds is chuffing which is not heard when bears are in good mood. Thus the chuffing sound suggests that the polar bear is not in a good mood at all. They never make chuffing sound while playing. Do you want to know what sound does a polar bear make in tundra?

    What Does a Polar Bear Sound Like?

    Icy bears are thought to produce as many as 3 to 6 different sounds. Each sound shows different behavior of an animal. The polar bear’s sounds include moaning, jaw-chopping, growling, blowing, hissing, whimpering, throaty rumblings, braying, squalling, smacking, roaring, and finally chuffing.

    If you come across a vocal polar bear you’ll notice that she might sound like a tiger or a lion when she roars. The roaring sound is not as clear though but it is good enough to give the impression of a tiger. Sometimes ice bears appear to sound like elephants.

    The sound roaring is sometimes is a call of excitement as most bears roar when they are in a fairly good mood. Aggressive calls include jaw-chopping and growling.

    What does a Polar Bear Sound when she is Angry?

    Polar bears make a repeated call of chuffing when they are angry. While they often avoid fighting and walk away the mother bear produces chuffing sound when she must defend her cubs against an intruder. Male polar bears regularly show strength to the outsider male but they do not do so in order to defend cubs. They will leave mother and cubs soon after mating. Male bears often fight to win over their mating partner. That is why the chuffing sound is typically heard in the mating season rarely in regular days.

    They will produce a chuffing sound with open mouth. Since they utter same chuffing sound in different situations it depends on the context as to what polar bears want to say. Studies suggest that adults also utter chuff sound when they are in distress. It’s like a ‘mayday’ call. While bears mostly live alone sometimes polar bears live in groups. If one of the group members get separated then she might utter a repeated call of chuffing.

    Read More: How do Polar Bears Communicate?

    what does a polar bear sound likeWhen do Female Polar Bears produce a Chuffing call?

    Female bears become more vocal in the first 120 days when they emerge out of their maternity dens. They do so in order to drive out all sorts of threats from her cubs. Unlike adult males female polar bears are devoted mother and they will actively respond to the distress call of their babies. The call is greatest when cubs are only few days old in age. However as the polar bear babies become 3 – 4 months old the mother produces call but only sometimes.

    The mother bear is also likely to chuff when she plays with her cubs. Sometimes she sniffs, or rubs her muzzle against her cubs, or when she bites and paws. She may utter the same chuff sound during all these actions. Similarly, if a mother bear attempts to change her posture she produces a chuff call.

    Polar bear cubs get separated from their mother after attaining one year age (sometimes two years). During this separation moment the mother and a cub will either roar or chuff. Scientists observed that when the mother chuffs the cubs actively respond to her call by coming nearer to her.

    When do Male Polar Bears produce a Chuffing Sound?

    The adult males go away and live a solitary life after mating but when the same male returns to the female (after 2 years) the entire family i.e. mother, father, and cubs begin to chuff. Observation suggests that males utter a chuffing sound when they copulate. Alongside chuffing they also moan during copulation.

    What do Baby Polar Bears Sound Like?

    Polar bear cubs are thought to utter a unique humming sound but they also chuckle during nursing. They also speak right after the birth but the vocalization is not so clear.

    What does a Polar Bear Sound Like? – Video

  • How Do Polar Bears Move? Polar Bear Movement

    Back in 1980s scientists studied the polar bear locomotion and established that polar bears were not energetically efficient walkers. The study was carried out not in the natural environment. In fact scientists observed bears walking on treadmills. According to them, polar bears consume more oxygen and heat storage in comparison to other land mammals.

    They thought that the polar bear’s morphology was not well developed for it to walk rather efficiently. The long forelimbs of an ice bear is meant to capture more than anything else. Polar bear’s excellent hunting strategy and thermoregulation is what makes them a serious predator. However, they are the most mobile animals of all quadrupeds. Scientists have yet to discover the locomotion in polar bears in their natural habitat.

    How Do Polar Bears Move Around?

    Polar bear travels vast distances using cues to navigate through the arctic habitat. Scientists believe that they need to understand these cues in the light of bear’s own locomotion without comparing it to the movement of other species.

    Polar bear’s walking is its most familiar gait and it looks like pigeon-toed because bear’s forepaws are directed inwards. They are able to gait as well as gallop but they cannot trot.

    Polar bear’s walking is its most familiar gait and it looks like pigeon-toed because bear’s forepaws are directed inwards. They are able to gait as well as gallop but they cannot trot. If you happen to look at a walking bear from behind you can probably notice the prominent sway in her hips. Mature males often appear (during walk) as if their rear legs are turning around while viewing it from behind.

    how do polar bears move
    Image Courtesy: Educational Technology Clearinghouse – University of South Florida

    Polar Bears Walking Speed

    Goes without saying that polar bears are not proficient walkers as much but their typical gait speed is about 5.5 km/h. Furthermore, bears can maintain this much for extended period of time. They do however relax a little during the journey. The minimum gait speed is around 1 km/h. Scientists noted the average speed of 4 km/h which they were able to sustain for as long as 20 hours. Few specimens did show up maximum stamina as they were able to sustain 4 km/h for up to 40 hours.

    Polar bears are not proficient walkers as much but their typical gait speed is about 5.5 km/h. Scientists noted the average speed of 4 km/h which they were able to sustain for as long as 20 hours.

    During warmer months in the Hudson Bay polar bears appear to remain inactive; the walking habits become limited throughout the season. They do nevertheless charge for their alternative prey such as waterfowls and caribou. Typically ice bears are slow animals for they never sprint like tigers do. The heat which is produced during the activity is likely to be dispersed in a very little time consequently leaving nothing to store. The maximum limit for polar bear walking is about 7.9 kilometers per hour.

    Polar Bear Cubs Walking

    Studies suggest that polar bear cubs get too tired in too little time. This is due to the number of strides they have to take in order to keep up with their mother’s speed. Since number of steps is going to define the energy cost per gram of a body weight. The greater is the frequency of steps the greater is the energy consumed.

    Adults on the other hand do not seem to require too much energy (in walking) for while they are heavier the longer strides help them to cover the same distance in less time.

  • Polar Bear Skull – Skull Information and Facts

    Polar bears (Ursus maritimus) are the most powerful terrestrial carnivores in the Arctic Ocean. In this article we are going to tell you interesting facts about polar bear skull and how it is different from other bears. They will share many morphological features with other strongest carnivores. Carnivorous animals have certain physiological features in common such as jaw, teeth, claw, eyes, and skull. Archaeologists and scientists have long researched the skull of Ursids let alone polar bears. In northern Alaska archaeologists discovered the king polar bear skull following the 2014 storm. The skull tells us about 1,300 years old ecological behavior.

    Polar Bear Skull

    The polar bear’s skull is a typical of any other land carnivores. Bears unlike other carnivores have relatively deep and flattened mandibular fossa. The mandibular fossa is called jaw hinge. Polar bear’s jaw can hardly move sideways though it opens up and down quite freely. The jaw hinge resembles dog’s mandibular fossa.

    Definition of Skull

    The skull is often defined when describing the entire skeleton of the head. Sometimes only cranium comes under the definition of a skull. The cranium is a part that encloses brain, sensory organs, and head. The primary characteristics of an animal are often defined in respect to the primary characteristics of a skull.

    Polar Bear versus Brown Bear’s Skull

    As compared to the brown bear’s the polar bear’s skull appears to be longer and elongated. They also possess longer nose than brown bears. The principle characteristics of a skull are same in all bears with only few differences. Here we are going to discuss polar bear’s skull and compare it with brown bears’.

    Polar bears have one of the largest skulls in the bear’s family—second only to brown bear’s skull. Viewing it laterally the brown bear’s skull seems like little wider whereas white bears have narrower skull across the palate. This is primarily because condylobasal length to zygomatic width ratio is greater in white bears.

    The length-width ratio finally makes the skull narrower. The length-to-width ratio in brown bears is 1.59 whereas in polar bears the ratio is 1.63. It appears as if ratio calculations do not reflect as much the actual difference of the skull because in reality the difference should be more than it suggests. Calculations aren’t wrong but our perception may be! The reason behind the different visual impression is that brown bears have skull little taller as well as there is an overhanging occiput. Furthermore, there is no brow ridge in the brown bear’s skull the absence of which makes the skull rather curvy from canines to the cranium (brain, sensory organs, and upper jaw).

    polar bear skullKing Polar Bear Skull discovered in Alaska

    Archaeologists recently discovered the king polar skull in the northern Alaska. Scientists believe that the skull is one of the largest ever recorded in polar bears which is why they call it a king polar bear skull. The 16-inch-long skull is thought to be 1,300 years old. Besides, archaeologists also say that the discovery of skull might give us hints about indigenous people who lived alongside the mammoth predator.

    The king polar bear skull is likely to take us back in time predating 4,000 years old. Studies indicate that the skull is of an adult polar bear. The forward facing eyes resemble much to the modern bears but it is different from the modern bears. “We don’t know the exact size (of the entire animal), but we do know it was a huge bear,” Jensen, an Utqiaǵvik-based archaeologist, described.

    Polar Bear Skull – Video

  • What Color are Polar Bears? | Polar Bear Skin Color

    People often wonder if the polar bear’s fur is white then its skin is probably white too. That is not quite true. The polar bear’s skin is jet black which is in contrast to the bear’s white fur. One can hardly see the black skin except in situations when a polar bear sheds its hair possibly due to some disease or infection. The black naked portion of the body becomes prominent for as long as it is covered by the hair again. Let’s then discover what color are polar bears actually.

    What Color are Polar Bears?

    Unlike adults, the polar bear cubs have pink-colored skin especially in the first 150 days. Their skin turns black with age. On the contrary, grizzly bears have pink skin not only in cubs but in adults too. That said, white bears have eventually evolved to acquire black skin in adults—probably an adaptation trait. Let us not forget that the present-day polar bears have been evolved from grizzlies. Scientists do not know the primary reason behind this change.

    Back in 70s a group of scientists carried out a study in which they revealed that the bear absorbs ultraviolet light. They thought that the bear’s fur serves as a fiber optic filament in that they transmit light all the way to the skin. This is a sort of thermal warning. Andrew E. Derocher writes in his book, Polar Bears—A Complete guide to their Biology and Behavior, “Fibre optic properties of a polar bear hair appears to be less than a thousandth of a percent of the light traveled 2.5 cm (1 inch).” The loss of ultraviolet light is thought to occur in a fraction of that distance. As it turns out the theory of fiber optic fur does not stand to logic. Yet another reason is that there are certain regions in the Arctic where the sun never sets—at least 6 months a year in summer. Similarly in winter the darkness lasts for nearly half a year. During these days polar bears do not and should not retain the heat—they drive it away.

    Read More: Why are Polar Bears White?

    Polar bears occupy a vast range of Arctic Circle touching many territories including Russia, Denmark, Norway, Canada, and United States including Alaska. These countries have temperature that drops down below the freezing point. But polar bears are safe; thanks to the bear’s thick black skin which gathers sun-rays keeping the bear warm in cold weather.

    what color is a polar bears skin
    Polar bear’s black skin is visible.
    Image Courtesy: World Wildlife Fund

    Polar Bear Skin Color – What Color are Polar Bears?

    It is not only the black skin that keeps the bear warm in fact there is a dense layer of fat beneath the skin which measures 4.5 inches thick. However these fats do not prevent heat loss in polar bears as they swim in the icy cold water. The heat loss is prevented by the polar bear’s fur. Furthermore the thick fatty skin and fur do not allow white bears to run longer because if they do they’d become overheated.

    Read More: Why are Polar Bears White?

    The fatty layer of skin functions much like a thermos in which the heat is trapped keeping the thermos warm. Polar bears are remarkable swimmers and they are able to swim for days or even months if they must. If they had to swim without blubber the body temperature would drop down.

    This shows that the skin plays a significant role in defining the behavioral adaptation of polar bears. Cubs are however not protected by the blubber which is why mother bears mostly hesitate to swim with their cubs. Adult polar bears gain fats by eating seal’s blubber.

    What Color are Polar Bears? – Video

    YOU MIGHT LIKE TO READ?

    • WHERE DO POLAR BEARS COME FROM?: The polar bear and brown seems to have one evolutionary ancestor. Scientists estimate that both species set apart during the latest glaciations…
    • POLAR BEAR GENETICS: Polar bears appear to be genetically divided into discrete populations based on their geographic locations…
    • POLAR BEAR METABOLISM: Polar bears are thought to use numerous physiological and behavioral mechanisms to normalize temperature…
    • POLAR BEAR LIFE HISTORY & BEHAVIOR: Polar bears have long been the primary source of meat and other raw materials for indigenous people…

  • How Do Polar Bears Reproduce? | Polar Bear Reproduction

    The polar bear reproduction likely occurs in days when the seals are abundant. They will reproduce in March or mid-April to May. A male bear will begin tracking the female 100 kilometers far off via smell. Once male gets to the female it insists his partner to mate. If a male finds another wandering male both fight over the female. The fight is not intense as much and the less dominant male usually withdraws. The winner is going to mate with the female. In this article you’ll come to know how do polar bears reproduce in the Arctic tundra.

    Polar bears are polygynous creatures in that their cubs may or may not belong to the same father. The mating partners however live and eats together for as long as 10 to 14 days. During these days ovulation occurs many times. Once the female gets pregnant she eats a lot of food and tries to gather as much fats as she possibly can. The pregnant mother will put on weight almost equal to that of an adult male. Let’s get on with some of the most interesting facts about the polar bear reproduction.

    How Do Polar Bears Reproduce? – Polar Bear Reproduction Facts

    The reproductive biology of a polar bear is not quite different from other bears. Polar bear’s estrus cycle ranges from March to May but the peak days begin in the first week of May. Coitus is most likely to stimulate ovulation. The fertilized egg is thought to be suspended until autumn.

    The gestation period of a polar bear is 195 to 265 days. Cubs are typically born in January but they may not come out of den until March. The average number of cubs is two but three are also common across some of its range especially in Hudson Bay.

    The weaning period ends in spring and the cubs become independent at the age of 2.3 years age. The female may not breed again until the end of lactation period which lasts for about 2 years. The reproductive interval in polar bears is 3 years.

    Read More: How Many Babies Can a Polar Bear have at Time?

    Newborn cubs weigh up to 0.6 kg at birth. They are born blind, hairless and toothless. However cubs may gain weight in a few days up to 10 – 12 kg. They will leave the den after achieving 12 kilograms of weight. The weight continues to increase quickly until the cubs turn one year of age.

    The mother will nurse their young with fat-rich milk. Female polar bears are thought to possess the most nutritious milk of all carnivorous mammals. The nursing peaks in the first year after birth but it gets low in the second year.

    how do polar bears reproduceThe birth doesn’t appear to occur in the same month throughout the arctic. In the Hudson Bay cubs are born in mid-November to mid-December. In some regions the birth occurs in the last days of November. In the Beaufort Sea female bears mostly enter into the den in the early December. In captivity the birth may occur as late as in December 27. The female body condition determines the timing of implantation.

    Male bears become sexually mature at 3 years of age but they are able to breed for as long as 19 years. Normally males attain maturity at 3 – 5 years age.

    The abundance of ringed seals primarily defines the productivity in polar bears. The greater is the number of seals the shortest is the reproductive age. In the Beaufort Sea, the ringed seals are not abundant as much and thus the bears attain maturity at 5 years of age. The female will give her first birth at 6 years age. In the Canadian High Arctic ringed seals occur in high densities. As such females breed at the age of 3 – 4 years of age.

    Read More: When Do Polar Bear Cubs Leave their Mother?

    The number of cubs born is thought to decline as the bear attains 14 years of age. Females are least likely to complete their reproductive cycles before 3 years interval. The interbirth interval increases with the increase in nursing. If the weaning period is about 2.3 years (mostly) the birth interval goes up to 3 years whereas if the weaning completes in 1.3 years then female is able to breed again after 2 years interval.

    How Do Polar Bears Reproduce – Video