International Polar Bear Day is celebrated annually on 27 February
Polar bears have long been seen as a symbol of the Arctic. I remember last summer when I heard that the temperature in the Arctic Circle exceeded 30 degrees, everyone panicked, worried that they would never see a polar bear again in their lifetime.
IUCN Red List of Threatened Species
While the current state of polar bears is not as sensational as those articles suggest, polar bears have long been classified as vulnerable on the IUCN Red List of Threatened Species.
On this International Polar Bear Day, I'm here to talk to you about the King of the Arctic!
How big are polar bears
In the photograph of Inuka at the Singapore Zoo, the green color on his body is due to the warm climate of Singapore, and the hollow hair is attached to the moss.
On April 25, 2018, innuca of Singapore Zoo, the world's first and only polar bear born in the tropics, left us forever. The Singapore Zoo promises that polar bears will no longer appear at the Singapore Zoo. It reminds me of polar bears at the Shanghai Zoo many years ago, but that was a long time ago. After the polar bear died, the Shanghai Zoo never saw a polar bear again. I don't know if you have ever had the privilege of seeing a living polar bear?
My deepest impression of them is one word —
big
Polar bears are currently the largest predators on land, reaching a shoulder height of 1.6 meters when standing on fours, and even approaching 3 meters when standing on both feet. What concept? Get a feel for what it's like to stand in front of a polar bear!
In our impression, bears are very strong, so let's compare other bears on earth with polar bears!
From left to right: Malay Bear, Panda, Sloth Bear, American Black Bear, Spectacled Bear, Asian Black Bear, Grizzly Bear (Brown Bear Subspecies), Cave Bear (Extinct), Kodiak Brown Bear (Brown Bear Subspecies), Florida Short-Faced Bear (Extinct), Polar Bear, Giant Short-Faced Bear (Extinct)
So in fact, the three cute protagonists in the cartoon "Our Naked Bear" should not be the same size!
Among the surviving bears, the only one that can distinguish it from it is the brown bear. It is not surprising that the brown bear is originally its close relative, and the geographical isolation of the polar bear and the brown bear is between 500,000 and 5 million years ago. So far, they have not been completely isolated reproductively, and there is still a phenomenon of hybridization.
Hybrid offspring of brown bears and polar bears
In 2006, scientists had discovered wild grizzly bears in Canada, with sporadic gray fur in their snow-white fur, bear arms longer than ordinary polar bears, two bear paws gray, a grizzly bear-like bulge on the back, two bear eyes with black edges, and a crisscross of canine teeth on the face. In the past, such hybrid bears could only be seen in zoos.
Polar bears' cold gear
Polar bears living in the Arctic are completely tailored for the extremely cold climate. I'll take you to get to know their cold gear.
Equip one Huge body
As mentioned above, polar bears are huge, and there is a theory to follow.
In 1847, the German biologist Bergman proposed Bergmann's law, which states that the body shape of the same kind of thermostatic animal will increase with the increase of the latitude or altitude of the living area. Because the heat is mainly dissipated from the surface of the object, the larger the volume, the smaller the ratio of its surface area to the volume, the smaller the relative heat dissipation area, and the stronger the cold resistance.
This law is followed not only by polar bears, but also by animals such as arctic wolves. The human body actually follows this law, so it makes sense for the northeast to produce strong men and Russian fighting peoples.
Equipped with two warm furs
How warm is the fur of polar bears to ensure that they will not freeze to death even if they swim in the water?
Like huskies, polar bears have double-layered fur. The inner layer is warm and fluffy, and the outer layer is 15 cm hard needle hair. Do you think polar bears are white? No! Hard needle hairs are actually hollow and transparent. Therefore, even if the polar bear's fur is completely wet, it will be erect and not knotted. And because the needle hair is smooth and sparse, the polar bear can easily shake the water off.
We often see polar bears rubbing around in the snow in documentaries, and it is not maliciously selling cuteness, it is using snow to suck away the moisture on its body.
Scientists have tried to photograph polar bears with infrared photographic equipment in the past, but because the fur is too insulated, the polar bears have not been displayed on film. Later, someone tried UV-sensitive imaging photography and found that polar bears absorbed light in the ultraviolet band and eventually turned black on the white ice. What's going on?
It turns out that these hollow, transparent needle hairs of polar bears act as light pipes, transmitting the ultraviolet short waves of sunlight to the bear's skin and playing a role in the polar bear's complex heat regulation system.
So what color is the skin of a polar bear? A closer look at the polar bear's face gives a glimpse of the original appearance of their skin – black. Black leather + transparent light guide hair, is the perfect combination of heat absorption tools.
Equip three extra thick layers of fat
The subcutaneous fat on polar bears is not what we usually call Fat in English, but Blubber. Polar bears, like other polar animals, can reach more than 10 cm of subcutaneous fat, and 50% of their body weight is fat.
Unlike the fat produced by obesity, these blobs are arguably the most powerful equipment of polar animals. Thick fat does not affect movement and body size, but instead provides additional buoyancy, allowing polar animals to feel more comfortable in the water. It also provides plenty of energy to ensure that the animals survive the season of food shortages. It can also provide predators with the most delicious and nutritious meals, and polar bears hunt seals mainly to obtain this layer of fat. So, for polar bears, people are definitely the hardest thing in the world to eat.
To ensure there is enough fat, polar bears are very fond of preying on seals. Ringed seals, bearded seals, saddle seals, and crowned seals are his main prey. Of course, polar bears are also not afraid of other things, including shellfish, crabs, walruses, beluga whales, narwhals, fish, musk oxen, walruses, hares, geese that cannot fly during the hair removal period, bird eggs, seaweed, tundra berries, and eat carrion.
When hunting, Pi was very happy
On the endless, unobstructed arctic ice, polar bear hunting methods are very skinny. One is "waiting for the rabbit." "After relying on the sense of smell to find the seal's breathing hole, sit and wait for a few hours. While waiting by the breathing hole, it piles up a wall of snow to cover itself, like this below.
Seals can't see me, can't see me, can't see me
This is the one with the highest success rate among polar bears' usual hunting skills, and the best opportunity for polar bears to replenish their energy in winter.
Self-hypnosis: I am a harmless ice floes, I am an ice floes, I am an ice floes...
The other is "latent approach". It sneaks up on the seal from the ice or underwater and then launches a surprise attack. It disguises itself as a harmless piece of ice, slowly drifts towards its prey, and then jumps up violently, killing it with one blow.
Crawl forward with your ass
When diving close to the seal on the ice, the polar bear's head rests on its front legs and slides slowly forward with its chest and front legs, making the most of any possible cover. However, the study found that polar bears can also walk like this when they are not hunting, which may be very fun to skin like this
Arctic life is becoming more and more difficult and bitter
Sea ice in the Arctic Ocean is rapidly decreasing. As a creature that is highly dependent on a single habitat, polar bears are closely linked to ice floes throughout their life cycle.
The latest estimates by U.S. scientists suggest that between 1953 and 2007, ice and snow in the Arctic disappeared by 7.8 percent every decade. Sea ice off the coast of Alaska has retreated 260 kilometers north, and polar bears here must swim a considerable distance to find strong ice. Polar bears are exhausted by the long sea feeding routes, and if they encounter strong winds and waves in the sea, they can easily drown in the sea.
In the past 20 years, as the Arctic ice has melted due to warming, the number of polar bears forced to travel long distances to find food has increased significantly. Studies have shown that every 1 week of early melting of snow and ice reduces the weight of polar bears by 10 kg. In Hudson Bay in northeastern Canada, every 1 degree Celsius increase in temperature causes female polar bears to lose 22 kilograms of weight, which directly affects the survival and growth of polar bears.
In a report, the American Geological Exploration magazine predicted that due to global warming and melting Arctic ice, the number of polar bears on Earth may decrease by two-thirds by 2050, including polar bears in Alaska. That is, at least 15,000 polar bears will die.
The warming climate also led to a 15 percent drop in polar bear fertility. Polar bear mothers with cubs will choose to hibernate in the winter, and the energy expenditure and milk conversion during hibernation are completely dependent on the fat in the mother bear's body, and the hibernating mother bear can lose half of her weight in one winter. But if the Arctic Ocean freezes late, the mother bear will not be able to store enough fat.
But the problem for polar bears now is not only the difficulty of hunting, but more importantly, the continuous flow of industrial waste to the Arctic through atmospheric circulation. Polar bears standing at the top of the food chain get these harmful substances from a variety of marine animals. A large number of toxic substances such as polychlorinated biphenyls, heavy metals, and chlorinated hydrocarbons have even led to the emergence of hermaphrodite polar bears, and the proportion is extremely high.
Network spoof diagram
So if polar bears were transported to the South Pole, would they be a little easier to survive? Not to mention that the climate and terrain of the Antarctic and the Arctic are completely different, did the penguins sign and agree to transport the polar bear to the Antarctic?
Why do we always say that protecting polar bears is protecting ourselves? This is not a feeble slogan, but a fact that we usually ignore.
Stills from the movie "The Day After Tomorrow"
Just like the environmental changes described in the American disaster movie "The Day After Tomorrow". Glaciers and sea ice are formed by fresh water, and massive melting of sea ice will lead to an increase in freshwater imports, disrupting the Earth's circulation system and eventually plunging Europe into severe cold. None of us want to see disaster movies come true, so protecting polar bears, protecting their world, is also protecting our common world.