Tag: Polar Bear Adaptations

  • Can Polar Bears Survive in Warm Climates?

    Can Polar Bears Survive in Warm Climates?

    Polar bears inhabit one of the coldest places on earth where the average temperature for the warmest month (July) drops down to 10 °C (50 °F). Arctic occurs at the northernmost part of the planet. During winter, alongside high winds, the temperature drops down to −40 °C (−40 °F) with the maximum lowest temperature recorded at −68 °C (−90 °F). So, how can polar bears live in warm weather?

    Can Polar Bears Survive in the Heat?

    No, definitely not! Polar bears have quite many adaptations to survive in extreme cold weather. They cannot survive in warm weather—not even for one day. Polar bears will probably die in minutes if they are bred in warm habitats. Furthermore, polar bears can sometimes get overheated even in Arctic weather if they run for a few minutes continuously. That is why they give up in most chases as the heat inside their body gets entrapped. Now let us study why can’t polar bears live in heat?

    Polar bears have Thick Fur

    Polar bears are perfectly insulated with dense white fur. The bear’s fur has two layers. The guard hairs and the dense underfur both of which keep the bear safe even in Arctic chilling weather. If somehow polar bears are transported to warm countries, they might not be able to survive the heat precisely due to their thick coat.

    Polar Bear Habitat Characteristics

    The sea ice and water are the essential characteristics of a polar bear. They can barely live without it for they use sea ice as a hunting platform. Polar bears catch seals on ice floes. If the weather gets warm as it does in summer, polar bears might not be able to catch seals because the ice disappears rapidly in warm climate. Over time the global warming has also rendered much of the polar bear population redundant.

    Polar Bear’s Prey Live in Cold Climate

    Polar bears live in cold habitats so as their prey. Their primary preys are seals which are not known to survive in warm weather just like polar bears. Thus it is reasonable to assume that if the weather somehow gets warmer in the Arctic (which is highly unlikely) the polar bears and seals are going to die for they are not so adapted.

  • Why are Polar Bears White? | Polar Bear White Color

    No wonder polar bears appear white for the most part of the year.–except for warmer months when the polar bear’s coat shows yellowish color which is probably due to the oil they take from seals. Compared to adults, young bears display pure white coat one that becomes yellow with age. In captivity however white bears display a shade of green color. The greenish shade is primarily due to the algae that grow inside the bear’s hair. Let’s discuss why are polar bears white all year round?

    Why are Polar Bears White all Year Round?

    • The polar bear’s fur isn’t actually white at all. It only looks like one. This is because there is no pigment in its fur which can change color. A pigment is a material that changes the color of the reflected material.
    • The bear’s furs are hollow and transparent as a result of which they reflect sunlight from the snow. The reflection indeed gives rise to white color. That is why polar bears remain white all throughout the year.
    • Polar bears are protected with 10-cm-thick hide and dense fur which prevent the animal from getting cold. However the bear becomes overheated when it runs longer. That is why polar bears do not usually run. Furthermore white bears cannot survive in warm temperatures exceeding 10o C (50o F) because of the thick fur.
    • The polar bear’s fur consists of two layers; dense underfur and external guard hairs. The guard hairs look white but they are in fact transparent. Both layers serve as leather jacket for polar bears in order to keep them warm even in minus 30 degree centigrade.

    Leaving aside the tip of the nose the polar bear’s entire body is absolutely covered with furs including bear’s foot, claws, and powerful legs. The density of furs is the greatest in all Ursids. No other bear species seem to have this much furred body—not even brown bears. Perhaps this is an adaptation to survive in the extreme cold of the Arctic. The polar bear’s foot is also furred because it provides an added support to walk comfortably on the slippery surface.

    READ: [How Do Polar Bears Adapt to their Environment?]

    why are polar bears white
    Image Courtesy: Ellen Cuylaerts, Underwater & Wildlife photographer (Reproduced with Permission)

    Why Do Polar Bears have Black Skin?

    • Back in 70s scientists studied the polar bear’s adaptations as to its ability to absorb ultraviolet (UV) light.  This was thought to be the remarkable discovery since it forced biologists to think that polar bears might possibly capture energy during the absorption of light.
    • Later findings further suggest the ability to absorb light helps the bear to retain stable body temperature in the harsh arctic environment.
    • The hollow hairs of polar bears (besides attaching algae) also serve as optic fibers in that they provide path to funnel UV light to the skin.
    • It also explains why polar bears have black skin. The black skin is able to absorb such energy without harm.
    • Scientists believe that the absorption of high-frequency energy is indeed an extraordinary adaptation of white bears. Thanks to this characteristic adaptation which has helped polar bears to become Arctic’s deadliest predator—the Great Bear of the North.
    • Sadly perhaps this unique adaptation doesn’t seem to bear any scientific explanation. In the late 90s the scientist Koon found out that the polar bear’s hairs transmit light probably not as efficiently as it absorbs UV light.
    • As the light enters the fur and attempts to go down the shaft, energy is lost or perhaps absorbed, inhibiting much of the energy to get to the skin.

    READ: [Why Do Polar Bears have Black Skins?]

    why are polar bears white
    PHOTOGRAPH BY Ilnar Salakhiev-AP

    What Color is a Polar Bears Fur? | Why Do Polar Bears have Transparent Fur?

    • Polar bears have surprisingly black skin which is visible when the bear loses hair possibly due to some disease. In a bright sunny day in the Arctic the polar bear’s fur looks white and clean. It happens because the fur lacks pigment.
    • That being said, if it lacks pigment the coat must change to any color it gets. As it turns out it does! The fur not only appears white in fact it shows quite a few colors. When the sun rises or sets the polar bear’s coat takes on the yellow-orange hues.
    • Similarly the fur also plays blue color because sometimes the sunlight while passing through clouds and fogs bring blue light.
    • Polar bear’s fur is adapted to take on different colors from the surroundings primarily due to the nature of its hair. The bear’s hairs possess hollow medulla (core) which entertains the impurities.
    • They seem to show pure white coat soon after molting. During spring when the prey density is higher in the arctic waters adult males take on yellowish coat. The off-white or yellow coat is mainly due to the impurities or oil attached to the prey (seals).

    Polar Bear Molting

    Polar bears shed their hair in April to May but the shedding continues all summer. During fall the polar bear covers with shorter hair but in spring the hairs grow longer. They have thick underfur and pelt. The furs have varied lengths.

    Why are Polar Bears White? – Video


    References

    Kolenosky G. B. 1987. Polar bear. pp. 475–485 in Wild furbearer management and conservation in North America (M. Novak, J. A. Baker, M. E. Obbard, and B. Malloch, eds.). Ontario Fur Trappers Association, North Bay, Ontario, Canada.

    Lockwood, Sophie (2006). Polar Bears. Chanhassen, MN: The Child’s World. ISBN 1-59296-501-6.

    Koon, Daniel W. (1998). “Is polar bear hair fiber optic?”. Applied Optics. 37 (15): 3198 3200. Bibcode:1998ApOpt..37.3198K. doi:10.1364/AO.37.003198. PMID 18273269.