Ursus maritimus…that is the scientific name of the magnificent polar bear, the largest land-dwelling carnivore. These polar bears can be found in northern Greenland, Norway, Siberia, and Canada.
Polar bears are one of the largest mammals on Earth. Adult male bears can weigh up to 1,700 pounds and reach a height of eight to ten feet. Adult female polar bears weigh around 1,000 pounds and stand six to eight feet tall.
The name “sea bear” is quite fitting for polar bears, as they spend most of their lives in or around water. They are skilled swimmers but prefer to stay on the ice that covers the Arctic Circle for most of the year.
Why do polar bears spend so much time on the frigid Arctic ice? It is because the Arctic waters and ice floes are where they can find their favorite food – seals.
Catching seals can be challenging, so polar bears must hunt with stealth and patience. They also sometimes consume other animals such as walruses and dead whales. Fortunately, their white fur helps them blend in with the icy environment.
But how did polar bears, living in a snowy-white world, acquire white fur? Surprisingly, their hair is not actually white!
Their long outer hairs, which protect their soft and thick undercoat, are mostly hollow and transparent. The thinner hairs of their undercoat are also clear.
So why do polar bears appear white? The air spaces within their hairs scatter light of all colors, giving us the perception of whiteness when we look at them.
Some scientists propose that polar bears were once closely related to brown bears. Over time, they migrated to the Arctic and adapted to their surroundings. Gradually, they developed fur that helped them camouflage in the Arctic ice.
However, not all polar bears have white fur. Have you ever seen a polar bear in a zoo? If so, you might have noticed that its fur can appear almost green.
Scientists have discovered that algae from the pond water in the bears’ enclosures can cause the bears to turn green. They found that these algae grow inside the hollow hairs, not on the surface of the hairs!
Try It Out
Don’t you think polar bears are adorable? Continue learning about these cuddly creatures by exploring the following activities with a friend or family member:
- Scientists observe polar bears in their natural habitat to study them. They use radio collars to track the movements of the bears. Visit the Polar Bear Tracker online to learn more about how scientists catch, tag, and track polar bears in the wild!
- If you share our love for polar bears, make sure to visit the Polar Bear photo gallery. You will see polar bears in various environments. Which polar bears are your favorites and why? Don’t forget to share the gallery with a friend or family member!
- Imagine going on an arctic adventure. What could happen during your icy journey? Would you come across a polar bear, a penguin, or a seal? Write a story about your trip up North and share it with a friend or family member!
Sources of Wonder
- http://wwf.panda.org/what_we_do/where_we_work/arctic/area/species/polarbear/ (accessed 19 Sept. 2019)
- http://www.tundraanimals.net/guide/polarbear.html (accessed 19 Sept. 2019)
- http://en.wikipedia.org/wiki/Polar_bear (accessed 19 Sept. 2019)
- http://www.loc.gov/rr/scitech/mysteries/polarbear.html (accessed 19 Sept. 2019)
1. Why are polar bears white?
Polar bears are white because their fur is made up of two layers: a dense undercoat and longer outer guard hairs. The outer guard hairs are actually transparent and appear white because they scatter and reflect light. This adaptation helps polar bears blend in with their snowy surroundings, providing them with camouflage while hunting for prey.
2. How do polar bears stay warm in such cold temperatures?
Polar bears have several adaptations that help them stay warm in cold temperatures. Their thick layer of blubber acts as insulation, keeping their body heat in and the cold water out. Additionally, their fur is hollow, which helps trap heat and provides extra insulation. Polar bears also have a smaller surface area to volume ratio compared to other bears, reducing heat loss. They can also reduce blood flow to their extremities to conserve heat when necessary.
3. Are all polar bears completely white?
No, not all polar bears are completely white. While their fur appears white, it can actually range in color from pure white to creamy yellow. The color variation is due to factors such as age, genetics, and diet. Young polar bears may have a more yellowish tint, while older bears tend to have whiter fur. The coloration helps them blend in with their specific Arctic environment.
4. How long do polar bears typically live?
Polar bears have a lifespan of about 25 to 30 years in the wild. However, some individuals have been known to live into their mid-30s or even early 40s. Factors such as food availability, predation, and human activities can impact their lifespan. In captivity, where they have access to proper nutrition and medical care, polar bears can live up to 40 years or more.
5. Are polar bears endangered?
Yes, polar bears are considered a vulnerable species and are listed as endangered by the International Union for Conservation of Nature (IUCN). Their population is declining due to the loss of their sea ice habitat, which affects their ability to hunt and reproduce. Climate change is the biggest threat to their survival, as it leads to the melting of Arctic sea ice. Conservation efforts, such as reducing greenhouse gas emissions and protecting their habitat, are essential for the long-term survival of polar bears.