Polar bears are among the most recognizable animals in the Arctic. With their thick fur, powerful bodies, and ability to survive in freezing conditions, they are built for one of the harshest environments on Earth. Although they are often pictured walking across snow, polar bears are marine mammals because they depend so heavily on sea ice and ocean-based food sources.

Most polar bears live across the Arctic regions of Canada, Alaska, Greenland, Russia, and Norway’s Svalbard area. Their lives are closely tied to sea ice, which they use as a platform for hunting, traveling, resting, and sometimes breeding. Scientists divide the world’s polar bears into 20 populations, some of which cross national borders.

A polar bear’s main food source is seals, especially ringed and bearded seals. The bears wait near breathing holes or cracks in the ice, then catch seals when they surface for air. Seal blubber is especially important because it gives polar bears the fat and energy they need to survive. When food is plentiful, a polar bear may eat mostly the skin and blubber rather than the lean meat.

Polar bears have several adaptations that help them stay warm. Their dense fur has two layers, and beneath their skin is a thick layer of fat. Interestingly, their fur is not actually white. Each hair is transparent and hollow, but it reflects light in a way that makes the bear appear white or cream-colored. This coloring also helps them blend into snowy and icy surroundings.

Despite their size, polar bears are strong swimmers. They can travel long distances across open water, although swimming requires much more energy than walking on ice. This matters because Arctic sea ice has been shrinking, forcing some bears to spend more time on land or swim farther between ice sheets. Land-based foods, such as birds, eggs, berries, or carcasses, may be eaten when available, but they usually do not provide the same energy as seals.

Female polar bears usually give birth in winter dens. Cubs are most often born in December, and twins are common. The mother stays in the den with her cubs until spring, nursing them while she does not eat or drink. Once the family leaves the den, the cubs begin learning the skills they will need to survive in the Arctic.

Today, polar bears are listed as vulnerable by the IUCN. The main long-term threat is the loss of sea ice caused by climate change, since sea ice is essential to their hunting and movement. Some populations are doing better than others, but the overall concern is that continued ice loss will make it harder for many bears to find enough food and raise cubs successfully.