The polar bear in Arctic.

Most bears are opportunistic omnivores – they eat whatever they can find, and plants figure largely in their diet. While polar bears will eat seaweed when stuck on shore, they only do this in desperation. Their true diet is pure meat and fat, from seals and whale carcasses. Meat and fat have more calories than plants, so polar bears get the most caloric intake out of every bite, and every ounce of hunting effort expended, to build their important fat layer discussed above. Thick Fur. Except for the tip of the nose, polar bears are entirely covered in fur. They have a very thick undercoat, which is even denser than the coats of other bears, as well as longer guard hairs. This insulates them from the cold, even when they are in water. Their fur is also hollow and transparent. (It was once thought that polar bear fur could also conduct UV light to the animal’s skin but this has been proven to be false. ) Their fur has another use as well: the hairs reflect light, making polar bears look white and helping them camouflage among the snow and ice.