If you’ve seen a photo of a polar bear in the Arctic, you’d be forgiven for assuming that they are white. But this is nature playing mind tricks on us, something that was realized when an infrared camera was used to look at them. So, what color are polar bears?
Polar bears are not white, they have black skin and two layers of translucent, hollow fur. However, they appear white because their fur reflects the white sunlight. This is why they may appear grey when it is cloudy and have a red tint at sunset.
Keep reading to find out more about the color of polar bears, including the reason why they might appear green in captivity or even yellow at certain times of the year.
What Color is a Polar Bears Fur?
Polar bears have two layers of fur; the undercoat and guard hairs. The two layers provide extra insulation for polar bears. Both layers of hair are translucent with black skin underneath, but despite this, they appear white.
According to the WWF, this is because the translucent hairs reflect sunlight which makes them look white. You might notice that they appear more grey in cloudy weather and even slightly red at sunset, again this is all down to the light they are reflecting.
Translucent hairs were first noticed in the 1970s when polar bears appeared as black on UV film1 (source: Polar Bears: A Complete Guide to Their Biology and Behavior, A. E. Derocher, 2012).
If you look at polar bears guard hairs under a microscope, you’ll notice that they are hollow inside. The trapped air provides extra insulation for the cold arctic climate and also helps them with buoyancy2 (source: Polar Bears, D.J. Tyler) which is one of the reasons why polar bears can swim so well.
New research has proven that the guard hairs can absorb any infrared heat emitted by the polar bear rather than losing it to the cold3 (source: Inside Science). This is another way the polar bear has adapted to survive the cold climate and explains why they appear black on UV film.
What Color is a Polar Bears Skin?
Underneath the translucent fur, a polar bear has black skin. This is an evolved trait as other bear species, including grizzly bears, have pink skin. Polar bear cubs have pink skin for up to five months after birth, but this will turn black as they mature.
Scientists are still unsure why the polar bear has black skin. It was originally thought that the black skin was part of a thermal radiation effect that would help polar bears absorb heat from the UV light of the sun.
However, this theory was later disproved as it was found that UV light did not pass through their fur. Plus, it didn’t make sense that polar bears would rely heavily on the sun for heat since there is no sun during the coldest parts of the year in the arctic5 (source: Polar Bears: A Complete Guide to Their Biology and Behavior, A. E. Derocher, 2012).
Why Are Some Polar Bears Green?
From time to time you might spot a polar bear with green fur, this is common in zoos or when polar bears are taken out of their natural habitat.
According to Professor Steven Amstrup of Polar Bears International, the green color is due to algae which grow inside tiny holes in their fur hair caused by abrasive pen floors.
These algae would not be able to grow in the arctic as the temperatures are too low.
Why Are Some Polar Bears Yellow?
Like other marine mammals, these seals have high amounts of fatty oil in their blubber which are ingested in large quantities by polar bears, eventually leading to the yellow coloring of their fur.
This is most likely to occur just before they shed their fur in May or June annually.
Are Polar Bears Black at Night?
At night, polar bears have black skin and translucent fur, just like in the day. If you shine visible light on a polar bear at night, it will still appear white due to the way the fur reflects light.
However, if you look at a polar bear through an infrared camera when there is no visible light, they will appear black.
What Color is a Polar Bears Tounge?
They are not the only animal to have a black tongue, others include blue-tongued skink, chow-chow dog, giraffe, Jersey cattle, and Sha-Pei dog.
There is little research as to why this is the case with polar bears, however, research relating to the blue-tongued skink suggests that a blue/black tongue may reflect UV light8 (source: Cureus, P. R. Cohen, Vol 11(11), 2019).
What Color Are Polar Bear Eyes?
Polar bears have dark brown eyes that face forward9 (source: Seaworld). Whilst humans require special goggles to protect their eyes from the sunlight reflecting off the snow, polar bear eyes have built-in membranes that filter out damaging UV rays10 (source: Guinness World Records).