Polar bears are the world's largest land predators. They top the food chain in the Arctic, where they spend most of their time on the pack ice or in the water, hunting down their favorite food - seals.
A single polar bear can consume 100 pounds / 45 kilos of meat at one feeding, and needs about one seal per week, or 50 to 75 seals per year, to survive. The bears eat as much as they can during the winter to get fat. They then live off the fat in their bodies during the summer when the ice melts and it is harder to catch seals.
The polar bear's white coat provides camouflage in the ice and snow, not for protection, but to make them almost invisible as they stalk their prey.
The fur is not actually white. Each hair shaft is pigment-free and transparent with a hollow core. It looks white because the hollow core scatters and reflects visible light, much like ice and snow does.
Beneath their "white" fur, polar bears have black skin, which absorbs more heat than pale skin, and under that skin is a blubber layer that can measure up to 4.5 inches / 7.2 cm thick. This, combined with the fur, makes the bears so well-insulated that they experience almost no heat loss.
But on bitterly cold days with fierce winds - and I mean REALLY cold - polar bears just dig out a shelter in the snow and curl up in a tight ball to wait out the storm.
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