The largest bear in the world and the Arctic's top predator, polar bears are a powerful symbol of the strength and endurance of the Arctic. The polar bear's Latin name, Ursus maritimus, means "sea bear." It's an apt name for this majestic species, which spends much of its life in, around, or on the ocean–predominantly on the sea ice. In the United States, Alaska is home to two polar bear subpopulations.
Considered talented swimmers, polar bears can sustain a pace of six miles per hour by paddling with their front paws and holding their hind legs flat like a rudder. They have a thick layer of body fat and a water-repellent coat that insulates them from the cold air and water.
Polar bears spend over 50% of their time hunting for food. A polar bear might catch only one or two out of 10 seals it hunts, depending on the time of year and other variables. Their diet mainly consists of ringed and bearded seals because they need large amounts of fat to survive.
Why They Matter
As one of the largest land carnivores in the world along with grizzly bears, polar bears are known as a keystone species, the apex of the ecosystem. They keep biological populations in balance, a critical component to a functioning ecosystem.
They’re also a sign of health for the ecosystem. If the keystone species is unhealthy, that’s a sign the entire ecosystem is in trouble. In the case of the Arctic, the health ofthatecosystem is a sign for what’s in store for the rest of the world.
Polar bears eat almost exclusively seals, but if they can’t hunt for that food source due to lack of a sturdy ice platform or pure exhaustion, they’ll quickly move on to others. This could threaten the existence of other Arctic species, like the Arctic fox or the walrus, as they compete for food resources.
Polar bears rely heavily on sea ice for traveling, hunting, resting, mating and, in some areas, maternal dens. But because of ongoing and potential loss of their sea ice habitat resulting from climate change–the primary threat to polar bears Arctic-wide–polar bears were listed as a threatened species in the US under the Endangered Species Act in May 2008. As their sea ice habitat recedes earlier in the spring and forms later in the fall, polar bears are increasingly spending longer periods on land, where they are often attracted to areas where humans live.
The survival and the protection of the polar bear habitat are urgent issues. In October 2019, the International Union for the Conservation of Nature (IUCN) released a new assessment of polar bear populations showing that the number of polar bear subpopulations experience recent declines has increased to four, with eight populations still being data-deficient.