To What Order Of Animals Does The Polar Bear Belong?

Polar Bear Cubs Photo Credit: Michael Henry

Polar Bear

Ursus maritimus

Condition: Threatened

Description

Polar bears are the largest cannibal land mammals on Earth. They are about seven to eight feet long, measured from the olfactory organ to the tip of their very short tail. Male polar bears are much larger than the females. A large male tin counterbalance more than one,700 pounds, while a big female is about one-half that size (up to 1,000 pounds). Bears can counterbalance nearly l percent more afterward a successful hunting season than they exercise at the start of the next; nigh of this additional weight is accumulated fat. A newborn polar deport weighs simply about 1.5 pounds.

Many of the polar carry's concrete adaptations aid information technology maintain torso oestrus and deal with its icy habitat. The bear'due south outer layer of fur is hollow and reflects low-cal, giving the fur a white colour that helps the acquit remain inconspicuous. The peel under the polar bear'southward fur is actually black; this black is evident only on the olfactory organ. Polar bears likewise have a thick layer of fatty below the surface of the peel, which acts as insulation on the body to trap estrus. This is especially important while swimming and during the frigid Chill wintertime. The bear's large size reduces the amount of surface area that's exposed to the common cold per unit of body mass (pounds of flesh), which generates heat.

The polar bear'due south footpads accept a kind of "not-slip" surface, allowing them to get traction on slippery ice. Polar bears accept potent legs and large, flattened feet with some webbing between their toes, which helps with swimming and walking on water ice. The wide paws prevent sea ice from breaking by distributing the polar bear'south weight as it walks. The webbed feet results in making polar bears, unlike other bear species, considered to be "marine mammals" along with seals, bounding main lions, walruses, whales, and dolphins. However, they are however bears. The polar acquit evolved one to three 1000000 years agone from the brown bear, which still ekes out a marginal life along the northern shore of the Arctic oceans. Unlike the massive polar bear, which can grow huge on a diet of abundant seals, its ancestor in the Arctic is small, has very lower reproductive rates, and eagerly eats near anything that exists in its environs.

Polar bears have evolved something else that is dissimilar from their ancestor: most polar bears don't den, however all chocolate-brown bears do. When grizzly carry nutrient is covered in snowfall during the winter, this species must den because there is cipher to eat. In contrast, well-nigh polar bears accept admission to their nutrient of selection (seals) all winter long, so there is no need for them to den. The exception to this is pregnant adult females. Significant female polar bears must den so that their tiny newborn cubs are born in a warm protected environment; dens can exist 38 degrees Fahrenheit warmer than the outside temperature. The cubs would otherwise freeze to death in the frigid temperatures of the far northward.

Range

Most polar bears occur north of the Arctic Circle to the North Pole. In that location are some populations s of the Chill Circle in the Hudson Bay of Manitoba, Canada. Polar bears live in Alaska, Canada, Russia, Greenland, and some northern islands owned past Norway, such as Svalbard.

Polar bears depend on the sea water ice, which forms above the open up waters where their seal prey lives. They volition spend time on land when sea ice is not bachelor (and near significant polar bear females make their dens on shore about the coast). Polar bears are excellent swimmers, and they travel long distances betwixt shore and the bounding main ice if necessary. Nonetheless, if a tempest kicks up during these increasingly long swims (caused by the warming ocean), they can drown. These long swims and storms are besides oftentimes hard for cubs. During periods of water ice breakup, polar bears ofttimes swim betwixt floating ice islands.

Permanent, multi-twelvemonth water ice that doesn't always melt is more of import to polar bears than the annual water ice that melts and reforms every twelvemonth; this multi-year ice is increasingly rare, but will likely persist for longer in the isle archipelago of northwestern Canada than in Alaska or off the northern coast of Russia.

Diet

Unlike other bear species, polar bears are virtually exclusively meat eaters (cannibal). They mainly eat ringed seals, only may also consume disguised seals. Polar bears hunt seals past waiting for them to come to the surface of sea ice to breathe. When the seal nears the surface, the polar carry volition bite or grab the seal and pull it onto state to feed. They too swallow walruses and whale carcasses. Polar bears will search out bird eggs and other nutrient sources, but none of these are abundant plenty to sustain the large torso mass and dense populations of polar bears.

Another vitally of import food source in most areas are seal pups that are born and live in dens in the Arctic ice. The polar bear identifies these dens past smell and other markers and pounces though the roof of the den to capture the immature seals. In Hudson Bay, the availability of seal pups in the leap is increasingly limited by before melting of water ice. In the Arctic, polar bears are at the top of the food chain; they eat everything and nothing (except native hunters) eats them.

Behavior

Polar bears tend to live solitary lives except when mating, when a female raising her cubs forms a family grouping, or when many bears are attracted to a nutrient source like a beached whale. Immature polar bears spending the summer ashore on the Hudson Bay coast will frequently play with each other, most normally with their siblings. Polar bears almost Churchill on the declension of Hudson Bay are even known to play with chained sled dogs without killing them, which they could easily exercise.

Life History

Polar bears breed in the tardily leap every bit the temperatures begin to rise in the Arctic. Similar other bear species, yet, they don't really go pregnant at the time of breeding every bit the tiny embryo (or blastocyst) will non implant in the female's uterus until fall, when true gestation starts. This is called delayed implantation and allows a female carry to physiologically assess her condition prior to starting gestation and the process of birthing, nursing, and conveying for her offspring for the side by side 3 years. The catamenia of actual gestation following implantation is only about 60 days.

In the Hudson Bay population, where the reproductive biology of polar bears has been well-nigh extensively studied, it appears that a polar bear female carrying a blastocyst must accomplish a body weight of at least 490 pounds to have the blastocyst implant and kickoff gestation. If this threshold is not accomplished, the blastocyst will reabsorb, the female will go on to hunt seals all wintertime, attempting to be fatter a year later on and able to carry off a successful pregnancy.

In the beginning of the wintertime, a pregnant female volition dig a den in a snowfall banking company and begin the process of gestation. Depending on the surface area, pregnant females may enter dens anytime between early Oct and December. The time of leave from dens occurs between tardily February and Apr. Well-nigh females dig their dens in a snow bank on country, simply some as well den on the floating sea ice. In Hudson Bay, females may dig a den in the footing instead, but they use areas where the snowfall will build upwards and provide insulation. In the centre of winter in some of the coldest places on Earth, female polar bears requite birth to cubs. Litter size is well-nigh normally two cubs, but sometimes litters can be one, 3, or, very rarely, 4 cubs.

Female polar bears in the Hudson Bay expanse spend remarkable periods of fourth dimension fasting, the longest known of whatever mammal species. This fasting period before denning and in dens averages about 180 to 186 days. In Hudson Bay, pregnant females can successfully fast for as long as 240 days. The long period of fasting makes this species particularly vulnerable to environmental changes like a warming climate, which reduces the amount of time they have available to build up the fat reserves they need to survive fasting and bring off a successful pregnancy.

When the cubs are born, they are completely dependent on their mother. They stay in the den nursing on her rich milk until spring, when they emerge and start exploring the world as their mother heads out to the water ice to catch the seals she needs to furnish the weight she'due south lost during her period of fasting. Over the next ii years, the cubs volition acquire from their mother how to catch seals themselves and to develop the other skills needed to survive and abound to adult size. Typically cubs volition stay with their female parent until they are two-and-a-half years old, simply in some cases they will stay for a year more or a year less. If the mother is able to replenish her fat reserves sufficiently, she tin can produce a litter of cubs that survive until weaning every iii years. When food declines in affluence, there is a longer menses between successive successful litters, and litter sizes are smaller. Polar bears in the wild tin live to be thirty years of age, just this is rare. Most adults die before they reach 25 years.

The weather developing in Hudson Bay are such that females will no longer exist able to nascency and successfully heighten a footling of cubs. When this happens, the adult bears will survive until they dice of old age and the population will be doomed. Scientists are fearful that this pattern is also starting to happen in the more northern polar acquit populations every bit the amount of Arctic water ice continues to compress.

Conservation

Polar bears are in serious danger of going extinct due to climate change. In 2008, the polar bear became the get-go vertebrate species to be listed under the U.S. Endangered Species Human action as threatened due to predicted climatic change. The Secretary of Interior listed the polar bear equally threatened simply restricted the Endangered Species Act's protections, and thus the polar acquit'due south future is all the same very much in jeopardy.

The primary threat to the polar bear is the loss of its sea water ice habitat due to climate modify. As suggested by its specific scientific proper noun (Ursus maritimus), the polar deport is actually a marine mammal that spends far more time at sea than it does on land. Information technology'south on the Chill water ice that the polar bear makes its living, which is why climate change is such a serious threat to its well-being. Polar bears are being impacted by climate modify in several ways.

Po pulation sizes are decreasing: In southern portions of their range around Hudson Bay, Canada, there is no body of water water ice during the summertime, and the polar bears must live on state until the bay freezes in the fall, when they can over again chase on the ice. While on land during the summer, these bears eat little or nix. In just 20 years, the ice-free period in Hudson Bay has increased by an average of xx days, cutting short polar bears' seal hunting season by nearly iii weeks. The ice is freezing afterward in the fall, but it is the earlier spring ice cook that is peculiarly difficult for the bears. They take a narrower time frame in which to hunt during the critical season when seal pups are born, and boilerplate conduct weight has dropped by 15 percent. The bears have fewer cubs, and of the cubs they do accept, the frequency of survival to adulthood is decreasing. In add-on, the interval between successful litters is growing. Every bit a result, the Hudson Bay population is down more than 20 percent. The patterns seen in Hudson Bay are beginning to occur now in more than northern populations and is especially well documented on the north declension of Alaska, only appears to be the instance worldwide.

Sea ice platforms are moving further apart: The retreat of ice has implications beyond the obvious habitat loss. Remaining ice is farther from shore, making it less attainable. After each summer, the trend seen in the Arctic is for sea ice to be farther from shore, making it necessary for polar bears to swim increasingly long distances from shore to reach the ice. Worse, the concluding remaining ocean water ice is over deep and unproductive waters that yield less prey. The larger gap of open water betwixt the water ice and country also contributes to rougher wave weather condition, making the bears' swim from shore to bounding main ice more than hazardous. In 2004, biologists discovered four drowned polar bears in the Beaufort Bounding main. Never earlier observed, biologists attributed the drowning to a combination of retreating ice and rougher seas. Every bit a result of rapid ice cook in 2011, a female person polar conduct reportedly swam for 9 days nonstop across the Beaufort Bounding main earlier reaching an ice floe, costing her 22 pct of her weight and her cub. As climate change melts sea ice, the U.South. Geological Survey projects that two thirds of polar bears will disappear by 2050.

Food scarcity is increasing: As body of water ice disappears for longer and longer periods during the tardily summer, polar bears are left with bereft time to hunt. Polar bears can only survive in areas where the oceans freeze, allowing them to chase seals living under, on, or in the frozen polar ice cap. Exacerbating the problems of the loss of hunting areas, it is expected that the shrinking polar water ice cap will also cause a decline in polar bears' favorite prey—seals. The reduction in ice platforms near productive areas for the fish eaten by seals is affecting the seals' nutritional status and reproduction rates. Polar bears are going hungry for longer periods of fourth dimension, resulting in cannibalistic behavior. Although it has long been known polar bears will kill for dominance or impale cubs so they can breed with the female, outright predation for food was previously unobserved by biologists.

Additionally, development is increasing in ocean floor exploration and offshore oil extraction in the open waters that were previously sealed past frozen ice. This brings people, disturbance, and potentially ruinous oil spills to the previously pristine Arctic polar bear habitat. Polar bears need our assistance and protection to ensure a long, good for you future for the species. The best way for people to assistance polar bears is past reducing carbon emissions and working with the National Wild fauna Federation to entrada for reductions in climate change pollutants.

5 Fun Facts

1. Considering they spend then much time in the ocean, polar bears are classified equally marine mammals. The polar bear'southward scientific name, Ursus maritimus, means "sea bear."

two. Polar bears evolved from chocolate-brown bears to survive in extreme northern environments.

3. Polar bears are the largest terrestrial predator on the planet, with large males continuing more 11 feet (3.3 meters) alpine on their hind legs and reaching weights over 1,700 pounds (770 kilograms).

four. Unlike black bears and brown bears, polar bears do not hibernate during the winter months considering that'due south when sea water ice forms, which the polar bears need to hunt seals.

5. When necessary or playing, polar bears communicate with each other with grunts, growls, roars, or squeals. What does a polar bear roar sound like? We hit the streets to pose this unproblematic question. Hear what people had to say: