If you were to dig a hole at the geographic North Pole, you might be amazed to uncover an ocean beneath your feet. That is because you are not standing on solid ground, but on an ocean-sized piece of floating ice on the Arctic Ocean.
The North Pole is a part of the larger Arctic ecosystem. The Arctic, a region including the lands and waters north of the Arctic Circle (66° 32’ N), is known for its frigid winter temperatures. Temperatures can drop so low that you can hear your spit crackle in midair as it freezes before it reaches the ground.
Warmer temperatures in the southern part of the Arctic Circle melt ice and snow to expose land briefly during the short summer season. Vegetation is composed of mostly shrubs, lichens, and mosses that grow close to the ground. These plants support herbivores such as lemmings, hares, and caribou. Carnivores such as wolves, bears, and arctic fox prey upon these animals. Warmer global temperatures are causing more ice to melt during the summer months. Although this may open the Northwest Passage to commercial sea traffic, it threatens animals that depend on the ice.
Out at sea, currents bring up nutrients from the ocean bottom. Producers thrive in the nutrient-rich waters and the extended sunlight during the Arctic summer months. Phytoplankton support a large diversity of aquatic organisms, including the largest sea animals—whales. The gray whales are baleen whales that feed on small crustaceans in the Arctic seas. These summer visitors have the longest migration of any mammal. Their 22,531 km (14,000 mi) journey takes 2–3 months and begins in their breeding lagoons in Baha California, Mexico.
Polar Bear Facts
Polar bears are the world’s largest land predators and the largest of the eight bear species. A male can grow up to 3 m (10 ft) in height and can weigh up to 771 kg (1700 lb). A female bear weighs about half that.
Nobody knows for sure how many polar bears are in the Arctic because it is difficult to collect a reliable population census. The estimate is around 25,000, and about 60% of them are in the Canadian Arctic.
Polar bears have special adaptations that allow them to survive the cold. Their translucent, hollow hair contains air that insulates the bear by creating a mini greenhouse. Although the hair appears white and blends into its surroundings, its skin is dark and absorbs energy from the sun. The bear’s small ears and tail reduce heat loss. A thick layer of fat, called blubber, lies beneath the skin. Blubber gives the bear buoyancy, because fat is less dense than water. It also insulates the bear by keeping the cold out and the heat in—especially when swimming in the frigid sea. The bears are so well insulated that sometimes the only body heat that shows up on infrared photography is from their noses!
Polar bear paws are especially adapted for this ecosystem. The bears use their large front paws to propel themselves in the water, the back feet are used to steer, allowing the bears to swim 160 km (100 mi) from the shore. Paw pads are rough to keep them from slipping on the ice, and broad, like a snowshoe, for stability on snow.
Being the top predator in the Arctic, polar bears eat almost everything, but their diet consists mainly of seals. The bears will stalk seals at their breathing holes and wait until a seal comes up for air. They also eat walruses, whales, fish, reindeer, and even bird eggs and berries when other food is scarce. Melting polar ice and longer, warmer summers in the Arctic are threatening the polar bears. In 1973, an international treaty was signed by countries inhabited by the polar bears with the goal of protecting and managing the population of bears, but their greatest threat is still the loss of habitat.