Polar bears are among the most iconic and majestic animals in the Arctic. Its massive size, incredible power, and stunning beauty have captured the imaginations of people around the world. But there is much more to these magnificent animals than their look. Are you ready to get into the world of these white bears with some of the most interesting facts below?
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Ursidae
Genus: Ursus
1. Polar bears are marine mammals
Spending most of the time on ice, the polar bear is the only type of bear that are classified sea mammal. This is reflected in their scientific name, Ursus maritimus, which translates to “sea bear.” Their activities, such as hunting, courting, and mating, take place on the ice, where they spend many months far from land.
Furthermore, polar bears are the world’s biggest carnivores at the moment. The adult often has a size ranging from 1-1.5 meters (3.3-5 feet) in length. While standing up on hind legs, a male can reach up to the height of 3 meters (10 feet).
Adult males typically weigh between 350 and 600 kilograms (775 – 1,300 pounds). On the other hand, females are typically lighter, weighing 150 – 290 kg (330 – 650 pounds).
Nonetheless, a bear’s weight changes substantially throughout the year. Some bears may gain up to 50% more weight after a good hunting season. They then lose weight during their fasting months.
| Size comparison: Polar bears vs grizzly bear vs brown bears vs hippo | ||
| Length | Weight | |
| Polar bear | 7 – 9 feet (2 – 3 meters) | 330 – 1500 pounds |
| Kodiak bear | 6.5 – 9 feet (1.96 – 2.74 meters) | 400 – 1500 pounds |
| Grizzly bear | 5.6 – 8 feet (1.68 – 2.44 meters) | 290 – 790 pounds |
| Hippo | 9.5 – 16.5 feet (2.9 – 5.05 meters) | 2,866 – 7,055 pounds |
2. They live in the sea ice
White bears, which are born on land, spend most of their lives on Arctic ice (the north pole). These bears can be found in 5 countries: Russia, Norway (Svalbard), the U.S. (Alaska), Greenland, and Canada. They don’t live in the south pole (Antarctica). That’s why you’ll never see penguins and polar bears together.
When compared to the other bear species, polar bears’ range is wider and they don’t have territories. Their home is determined by the condition of sea ice (whether it extend or retreat) and the quantity of prey.
3. Their main diet is fat
Polar bears consume the most meat of any bear species. However, these creatures don’t need protein in meat that much, they need fat (aka blubber) as their primary source of calories. That’s why refer to them as lipovores.
The majority of the fat they consume is absorbed straight into their own body fat. This fat provides them with warmth and aids in survival during periods of food scarcity. For polar bears, seal blubber is the ideal food source, and they can consume up to 45 kg (100 lbs) of it in one meal.
In good conditions, these white bears solely feed on the fat and skin of their prey. The remainder is left for scavengers such as ravens, Arctic foxes, and other bears.
Their primary food consists of ringed seals and bearded seals. However, when things are tough, they consume other food sources such as small mammals, geese, beached whales, bird eggs, and anything else they can capture with their claws.
However, among these prey, whales or walruses are the only food source that can give the white bears sufficient calories they need. With other food, they don’t have enough calories to maintain their body size and build up fat reserves.
Polar bears are apex predators in the Arctic, they’re on top of the food chain. According to scientists, they have no natural predators. However, these huge bears rarely attack us. A study conducted in 2017 found that there have only been around 20 people died because of the animal’s attacks over the last 144 years.
4. They need ice to catch food
Polar bears depend on the ice to hunt for their prey.
The seal drills holes in the ice to breathe. They appear at one of the holes every 5 to 15 minutes. The white bears wait patiently near these holes and use their acute sense of smell to locate the seals. They can smell a seal on ice from up to 20 miles (32 km) away. Once they spot their prey, they remain motionless for hours or even days, waiting for the perfect moment to strike.
In addition to hunting at breathing holes, polar bears also stalk basking seal on the ice. They move slowly towards their prey and stay immobile whenever the seal raises its head. Then, at a distance of about 6 meters (20 feet), the bears charge forward with explosive speed, catching and killing the seal with their sharp claws.
However, with the ongoing effects of global warming, Arctic ice keeps melting. This makes it hard for polar bears to get close to their prey. They have to move a longer distance to obtain prey. In some cases, the energy they expend trying to catch a seal may even exceed the energy they gain from consuming it.
5. They have black skin
Perhaps you don’t know this, but polar bears are not white! Yes, you heard it right! It’s like the blue animals you see are not actually blue. You can see the list of exclusively blue animals that are not blue here.
Back to the ice bears, their skin color is black and their hairs are transparent and hollow. These species just look white due to the scattering of light through their fur.
However, in captivity and under warmer temperatures, these bears can develop a green tint due to the growth of algae. The algae can grow inside each hair’s hollow tube, causing the bears to look green not only on the surface of their fur but also internally.
This phenomenon is most commonly observed in humid climates like Singapore, which is not a natural habitat for these bears.
6. Adaptions
Polar bears are adapted to survive in their extreme cold environment in the Arctic waters by possessing unique physical features.
Their thick fur, which consists of two layers, serves as a highly effective insulator that prevents heat loss. However, while in the water, they rely mostly on their fat to keep warm since wet fur does not provide insulation. To further minimize heat loss, polar bears have small, round ears and a short, dense tail.
Polar bears have enormous 12-inch feet functioning as snowshoes. This allows them to hunt on thin ice without falling. These paws are also well-suited for swimming, with their forepaws serving as enormous paddles, while their back paws function as rudders.
The bottom of the paws is adorned with black footpads that have tiny, mushy bumps called papillae. These bumps that are similar to those found on our tongues assist the bears in gripping the ice and preventing them from sliding.
Their large, curved claws, which can grow to be nearly 4 inches long, allow them to grasp onto slick prey.
7. They can become overheated
Polar bears are designed to endure extreme cold, but this can also make them vulnerable to overheating. They are unable to pursue prey for extended periods of time due to their thick fur coats and body fat. If they walk too quickly, their body temperature can increase to dangerous levels. This can cause them dead.
As a result, they often walk at a slow speed. They can run for a short distance before overheating.
8. They are pro athletes
Polar bears are skilled swimmers, they can swim 6 miles per hour (9.6 kph). Like the platypus, these bears seal their nostrils underwater. They can dive up to feet deep and hold their breath for over two minutes. This ability allows them to stealthily approach seals resting on ice floes.
A 2011 study revealed that a female polar bear, which had been tagged, swam for nine consecutive days across the Beaufort Sea north of Alaska, covering a total distance of 426 miles. Through this process, she dropped 22% of her body weight. In 2015, a bear set a new record for the longest dive lasting for 190 seconds (more than 3 minutes.)
Not only are polar bears skilled at swimming, but they’re also good at walking. Although they move pretty slowly, these creatures can move at a speed of 5-6 kph. Females with young cubs walk at a slower pace, averaging 2.5-4 km per hour.
The special thing is that they can roam up to 3,000 kilometers every month. Their home ranges can span over 600,000 km2, which is larger than the state of California.
9. Behavior
Adult polar bears live a lonely life, except for the mating season. However, they are known to socialize with each other on occasion, especially when there is a large food source, such as a whale carcass, available for multiple bears to feed on. During these times, male bears may engage in playful wrestling and swatting without actually hurting one another.
Unlike other bear species, polar bears do not need to hibernate during the winter. This is due to the abundance of food accessible to them on the sea ice during the coldest months
Although these giant bears don’t hibernate, they do take shelter during harsh weather. They dig shallow pits in the snow and remain there until the storm passes. In summer, they may rest on the sea ice using an ice block or their paw as a pillow. To keep cool, they may even dig into the permafrost or make sleeping burrows in the sand or stone ridges close to the coast.
Like us, polar bears sleep for 7-8 hours at a time and take naps, particularly after eating a seal. This is crucial for their conserving energy.
To maintain their insulation, polar bears prefer to be clean and dry. After eating, they wash for up to 15 minutes in open water, licking their muzzles, paws, and chest. Next, they shake off excess water and dry themselves with snow. The young cubs will be cleaned by their mothers and by licking themselves and each other.
To communicate, white bears use sound, body language, and scent trails. For example, charging forward with a head down and ears laid back signifies attack mode, while a lowered head indicates hostility.
Heads moving from side to side signals the desire to play, whereas nose-to-nose moves are used by bears to request something, like food.
Polar bears use a variety of sounds, including roars or growls, soft cuff, hissing, chuffing, growls, and snorting.
10. They spend a lot of time fasting
Polar bears spend a significant amount of time fasting when they are not hunting seals. In the book Bear Necessities, Lisa Kemmerer said that these bears could reserve roughly 150 pounds of food in their stomachs.
Among all mammal species, female polar bears fast for the longest duration. A pregnant female can hide in the den and doesn’t eat or drink anything for up to 4 – 8 months.
Due to the melting of sea ice, polar bears may have to endure even longer periods of fasting in the future. Less ice means fewer hunting opportunities. The bears have less time to build up fat reserves to survive through the tough season.
11. The baby polar bears live in dens
The mating season of polar bears occurs from April to late June. They use the scent from their paw sweat glands to follow other bears, as well as to feel where possible partners might be headed.
Mating occurs on sea ice. However, fertilization is delayed until the fall, contingent on whether the female has sufficient fat for herself and her cubs. This is known as delayed implantation.
The males stay with their mates for a few days before leaving.
In summer and fall, the females forage and accumulate as much weight as feasible. They then excavate a den to give birth and nurse their cubs. The entrance tunnel of the den is then covered by snow, concealing the den entirely.
The females spend their gestation period in the den during the harsh Arctic winters, waiting for their cups to be born in December. They will have 1-3 cubs, usually twins. Newborn polar bears are completely reliant on their mother. They are blind, toothless, measure 30-35 cm (12 to 14 inches) in length, and weigh slightly more than 1/2 kilogram (1 lb).
However, they grow quickly under the nourishment of their mother’s milk, which is the fattiest milk found on land. This milk contains around 31% fat when the cubs are born, giving them enough energy to grow quickly. The young will continue to take milk for at least 20 months.
It takes about three months before the cubs venture outside. In March or April, they begin taking short trips outside the den and gradually become accustomed to the freezing temperatures. At this time, their cubs can weigh 15-30 pounds. At the age of 8 months, their weight can reach 100 pounds or more.
The mothers begin to show their young how to hunt and how to thrive in the Arctic. The cubs typically remain with their mothers for 2.5-3 years to learn essential skills such as hunting, swimming, feeding, and survival.
Female polar bears reach sexual maturity at the age of 4 – 6 years old. The males mature later, between 6-10 years. In the wild, polar bears have a lifespan of 15 to 18 years, some species can live for 30 years.
12. They have hybrid offspring
Polar bears’ mating habits are being affected by climate change. Melting ice forces them to stay more on land, where their ranges increasingly overlap with those of grizzly bears.
This overlap is resulting in increased interbreeding between the two species, particularly in Alaska and western Canada. This led to the cross-breeding between them, creating the hybrid offspring known as a pizzly bear.
While still uncommon, the population of pizzly bears is growing. They have features of both parents, such as light brown hair, a thin, pointed nose, and muscular shoulders.
13. They are going extinct
According to the ICUN, the polar bear is listed as a vulnerable species. It’s the first mammal to be classified as threatened primarily due to global warming. Their numbers keep decreasing.
The ice that they call home is melting due to climate change. As a result, appropriate hunting sites for them are diminishing, causing them to move longer distances to find food. This, in turn, has led to declines in fat storage, causing stress, in some cases, death.
Additionally, organic perseverance pollutants like mercury have a severe impact on the health of polar bears. These pollutants enter the bear’s systems through the food chain, affecting their reproduction, immune systems, and thyroid function.
References:
- https://polarbearsinternational.org/
- https://www.mentalfloss.com/article/532061/25-icy-cool-facts-about-polar-bears
