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All Creatures,

Episode 9: Ice Bear, aka The Polar Bear

December 26, 2017

Most everyone knows something about Polar Bears. However, there are so many incredible physical adaptations these bears have that help them survive the extremes of the Northern Polar regions.

Polar Bear History

The Polar Bear (Ursus maritimus) belongs to the family Ursidae. These also include other species such as the:

  • Brown (grizzly) bear (Asia and North America)
  • Black bear (Asia and North America)
  • Sun bear (Asia)
  • Sloth bear (Asia)
  • Spectacle bear (South America)
  • Panda bear (Asia)

Most bears have 74 chromosomes, but the Spectacle bear has 52, and the Panda bear has 42. Some hybrid Polar and Brown bears have been found in regions of the world, though it is believed these animals are infertile, or cannot breed.

Bears are a young mammalian family and date back 20 to 25 million years. The earliest ancestor was called Cephalogale and resembled a bear-dog animal. Polar bears specifically, and backed by DNA evidence, split from Brown bears approximately 400,000 years ago.

The largest known ancestor of today’s modern bears was a species of bear called Arctotherium in South America. This animal stood greater than 10 feet (3 meters) tall and weighed an estimated 3,500 lbs. (1500 kg). This bear went extinct approximately 11,000 years ago.

Polar Bear Habitat

There are 19 specific populations of Polar bears that live in the northern polar regions of the Artic. These populations are located in North America, Asia, and Europe.

During the dark and cold winter months, Polar bears, rather than hibernating like their cousins, are out on the Arctic ice hunting. Thus, they are often considered a marine mammal. The winter months are critical for their survival as they put on weight to survive the summer months.

During the summer after the ice melts, Polar bears spend most of their time fasting and sleeping on land. This is a time when bears will lose weight and must conserve energy until the following winter. An omnivore diet of fruit, plants or other smaller animals will not sustain a Polar bear, unlike other bear species.

During the winter months Polar Bears hunt for their number one food item, the ring seal. These seals are heavy with blubber (fat), which aid the Polar bears in putting on weight. Climate change has been drastically altering the polar regions, with less months of frozen sea ice. With less months to hunt Polar bears are having less time to eat ring seals and are forced to land earlier in the year. This is also having drastic (trickle down) affects on other species, as Polar bears turn to other sources of food such as birds, by eating  the young fledglings or eggs.

 Polar Bear Physiology

These bears have incredible adaptations that allow them to survive in harsh cold conditions.

  • The weight of a Polar bear can at times be almost 50% fat; helps insultation and also buoyancy when swimming
  • Polar bears have a larger mass to conserve energy, with smaller ears and tails for less heat loss (Bergmann’s Rule)
  • These bears have two layers of hair. An inner wooly layer for warmth, and an outer greasy layer to act as water repellent
  • Outer hairs are actually clear and hollow, not white. Light reflections make them appear white
  • Massive paws 12 in (30 cm) across that act as snow shoes and help them swimming
  • Excellent night vision for the dark winter months
  • Can run as fast as 22 mph (35 kph) and cover 4,000 miles (6500 km) per year

Polar bears are incredibly unique in their ability to survive on high fat diets. The blubber they get from seals, walrus and dead whales that they eat has elevated levels of low-density lipoproteins. These LDLs are often considered the “bad” cholesterol that leads to heart disease in humans. Scientists are now trying to understand how the Polar bear can survive and thrive with these fat diets.

Conservation Efforts

Current populations estimates have Polar bear populations at 20,000 to 26,000. A correct count is very difficult due to the location of these animals. However, due to changing climate conditions the IUCN lists Polar bears as vulnerable.

With current climate estimates, some are predicting the polar ice will be completely gone during the warm winter months. Thus, predictions for Polar bears are they will suffer a 30 to 50% reduction in population in the next 50 years. Since Polar bears are strictly carnivores, and have evolved to survive on the ring seals, they are at an extreme risk of extinction. Polar bears cannot and will not have time to adapt to an omnivore (fruit, plants, other animals) diet for their survival.

The number one conservation effort needs to be a reduction in carbon emissions from all people across all continents. Everyone should strive for a carbon neutral lifestyle. Here is a neat Carbon Neutral Calculator anyone can use to lead a healthier life for our planet.

Organizations to Support

Cincinnati Zoo Polar Bear Challenge

Polar Bear International

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