Why Clear Polar Fur Appears White

The polar bear's fur appears white to the human eye because of light refraction through the colorless hair to the hollow shaft which scatters and reflects white light.

  1. Fur

    • Ursus maritimus (polar bear) is one of the largest carnivores on Earth.

      A polar bear has two levels of fur: a dense undercoat that insulates and a coat of guard hairs. Each hair is pigment-less and has a central, hollow shaft. The bear's skin is black which, with the fur, helps prevent heat loss.

    Light Reflection

    • The polar bear was listed under the Endangered Species Act on May 14, 2008.

      Light from the sun is white and includes all the colors of the spectrum. When a beam of light hits an object, some of the wavelengths are absorbed and some are reflected away from the object. The color wavelengths reflected away from the object can be captured by the eye and the object is interpreted as that color. A polar bear's fur is pigment-less, it does not absorb any wavelengths of color. The hollow shaft of the hairs act as a diffusion filter which spreads the white light in multiple directions and allows the eye to see the bear as white.

    Green Fur

    • In captivity, polar bears can appear green or green-tinted. This is due to algae colonies growing within the hollow shaft of the hairs. The algae has not been shown to harm the animal and can be treated with a salt solution in the pond of the enclosure.