Tuesday, 2 January 2007
Polar Bears are impressive, beautiful and dangerous. Well adapted to harsh climatic conditions and known for their skill in stalking seals, polar bears are the symbol of the Arctic. They are not only the largest bears but also the largest land living carnivores.
Insulation
Polar bears are insulated from the extreme cold. Their bodies can hold heat much better than smaller bodies.
They have a thick fur coat which is made of hollow and translucent hairs (not white hairs as many thinks). The hairs transmit the sun’s heat to their bases where it is absorbed by the black skin. These hairs also stop the undercoat from matting when wet. Water is easily shaken off before it can freeze. The bear also rolls in snow to shed moisture from the coat. Beneath the skin is a thick layer of fat called blubber to keep it warm.
Soles
Did you ever wonder why polar bears never slip on the slippery ice? This is because the soles of polar bears are not only lined with fur but also covered with microscopic soft papillae (tiny projectiles) to increase friction between the paw pads and the ice.
Swimming
Polar bears are also excellent swimmers. They are quite buoyant because of their body fats and hollow hairs. They use their front paws as oars and dog-paddle with ease. Their hind-legs act as rudders.
They are able to swim for hours, especially in the summer. They are capable of swimming for 100km at an average speed of 10km/hr, without stopping.
Diet
The polar bear feeds mainly on seals, especially ringed seals that poke holes in the ice to breathe, but will eat anything it can kill: birds, rodents, shellfish, crabs, beluga whales, and young walruses, occasionally musk oxen, and very occasionally other polar bears.
Polar bears are at the top of the food chain where orcas, humans, and larger bears of their own species are their only predators.
Stalking & Still Hunting
Polar bears hunt in two different ways – by stalking and still hunting. 
Stalking begins when a polar bear spots a prey in a distance. It then lowers its head and walks slowly towards the seal. When the bear is 15 to 30 metres from the seal, it then charges suddenly. They can also swim instead of walk and surface from the water to claw its prey.
Still hunting is the main method of hunting. The bears lie on its chest and stomach with its chin closer to the breathing holes of seals. They then wait patiently for a seal to come up to air. In a single moment, they bite the seal on the head and flip it out to the ice.
Mating
Polar bears mate in the spring; pairing is temporary and only lasts for the actual mating; males and females form no permanent bond. The gestation period is 240 days (8 months), and the cubs are born in early winter in a cave dug by the mother in deep snow in October. Usually, two cubs are born.
The cubs are born helpless and blind, and open their eyes at about one month old, are able to walk at 1.5 months, and start eating solid food at 4-5 months. They remain with their mother, learning how to hunt and protect themselves against adult males until 10 months old. Females nurse their young for up to two and a half years on milk that contains approximately 33% fat. Sexual maturity is reached at 3-4 years.
Adult polar bears are known to live over 30 years. Polar bears do not hibernate, though lactating females will not emerge from their cave while the cubs are very young; they often go without eating for a period of nine months and rely on stored body fat (also known as blubber) to keep themselves and their cubs alive.
Threats
There are also many threats which polar bears face.
An example is climate change. Global warming would mean a rise in the Earth’s temperature. This would greatly affect polar bears as they easily overheat at a temperature of 10 °C (50 °F).
Other threats which polar bears face are pollution, industrial activities (mining/drilling), and poaching.
Citation
http://en.wikipedia.org/wiki/Polar_bear
2004, Wildlife Wonders Volume 4
Environmentalist Blogged:00:22
Polar bears are also excellent swimmers. They are quite buoyant because of their body fats and hollow hairs. They use their front paws as oars and dog-paddle with ease. Their hind-legs act as rudders.
