Polar Bear Facts– Ursus maritimus
These Sea-Bears may be Shrinking Due to Climate Change
Aug 28, 2009
Polar bears are the world's largest land carnivore. They have large skulls, short tails and thick legs. Their necks are longer than other bears' necks to assist when they lunge after prey. Polar bears have white fur, which enables them to blend with their surroundings; however, their skin underneath is black.
They are well suited to the cold of the Arctic Ocean, along the Hudson Bay and regions of Alaska and Canada where their range extends. Their thick fur, insulating fat layer and even furry paws help them to retain heat. The fur on their paws also gives them good grip on the ice. They can sprint up to 40km/hour after which they would need to jump into the ocean to avoid overheating.
The polar bear is a powerful swimmer and their fur is virtually waterproof, their hair shakes free of water and ice once the polar bear is on land. They can swim for large distances for several hours if necessary. They have been known to swim continuously for 100km (62miles) and can swim at speeds of 10km/hour (6.2mph). Interestingly, a polar bear’s nostrils close underwater.
The Current Taxonomy of the Polar Bear:
- Kingdom: Animalia
- Phylum: Chordata
- Class: mammalia
- Order: Carnivora
- Family: Urisidae
- Genus: Ursus
- Species: U. maritimus
What Does a Polar Bear Eat?
The polar bear diet includes seals, reindeer, seabirds, fish and even berries, but its preferred meals are ringed seals and bearded seals. They have also been known to kill young beluga whales or walruses and often will scavenge at carcasses of whales and walruses.
Polar bears will either swim in search of food or ambush seals at breathing holes when they come up for air. The bears have been known to wait longer than an hour if necessary. They have also been known to sneak up on prey across the ice.
They have an excellent sense of smell and can locate prey from kilometers away or dig through the ice to locate seal dens and eat the seal pups within. Polar bears have no natural enemies apart from the Alaskan Inuit (Eskimo), who kill them for meat and skin/fur.
The Sexual Behaviour of Polar Bears
Maturity for polar bears is 4 years for the female and 6 years for the male. Polar bears conduct a playful fighting session as a means of courtship before they eventually mate. Breeding takes place in April and May on the sea ice and usually 1-4 cubs are born every 2-4 years after a gestation period of 195-265 days.
Mothers and cubs bond strongly and cubs will stay with their mothers for 2-3 years. Polar bear cubs are born with their eyes closed and their fur is very fine. Polar bears grow to 2-2.5 meters (6.5-8.25ft) tall and weigh in at 150-500kg (330-1100lb). Lifespan for the polar bear is approximately 30 years.
Why are Polar Bears Getting Smaller?
Scientists in Denmark have discovered a reduction in the size of the skulls of polar bears and are concerned that this could affect their ability to survive. By investigating skull size, scientists are able to determine the body size of a polar bear and they believe that the reduction may be linked to climate change.
Due to temperature increases and more so because of a reduction in sea ice, it appears as though polar bears have to spend more energy moving around and that leaves less for growth. Chemical pollution is also under the knife as it is causing a reduction in fertility rates.
While polar bears are not considered endangered or even at high risk of extinction, it appears as though they are conservation dependent, so it is something that conservation groups and scientists will be monitoring.
Resource and further reading:
For more information visit the Polar Bears page on the Sea World website or the ABC article Climate Change Shrinking Polar Bears.
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