What is everyone's first impression when it comes to polar bears? I bet that at least eight adults answered in that beautiful and shiny "white coat".
The author is no exception, the first time I saw a polar bear in the aquarium, I was deeply attracted by the white and smooth fur, and a question suddenly appeared in my heart: Is the polar bear's hair all white?
What is the truth, let's study it together!
Photo with polar bears. Image source: Courtesy of the author
01
Oolong! Albino brown bear "freezes into dogs" in the Arctic
The story of "Albino Brown Bear" Joey is an oolong caused by white hair, let's review this story.
Joey is a brown bear with albinism, so he is white all over. Still, Joey lived happily in the forest until an animal protection organization discovered it. The group insists Joey is a polar bear because global warming has caused polar bears to migrate south in search of food.
They gave Joey anesthesia and secretly sent it to the North Pole. However, as a brown bear, Joey can't withstand the freezing temperatures and doesn't know how to find food. After careful observation and confirmation, it was determined that Joey was an albino brown bear and returned to the forest.
However, within a few months, another animal protection organization found it, repeated the same rescue process, and returned it to the Arctic, and netizens called Joey the "unlucky bear" Ben Bear.
Screenshot of Joey's story with the albino brown bear. Image from the Internet
However, the reversal soon came, and Joey's story was actually all fake. The so-called "albino brown bear" in the picture is actually a subspecies of the American black bear, the Komod bear, whose white hair is not due to albinism, but only a recessive genetic trait of the species.
Moreover, no animal protection organization has rescued it, after all, animal protection organizations are professional.
The Komod bear, also known as the "white spirit bear" or "ghost bear", is a subspecies of the American black bear that lives on the central coast of British Columbia.
02
Astound! Polar bears' fur is not white
Some friends may ask: The coat color of polar bears also looks white, is it also albino species?
Polar bears' fur looks white, but in reality their fur is not. Polar bears' hair has a very special structure, which allows them to adapt to the cold polar environment. Studies have shown that polar bears' hair is transparent, not white.
The hair of polar bear skin is divided into two layers: the outer layer is a long protective hair (5~15 cm), and the inner layer is a short thick undercoat. Hair guards are made up of a protein called keratin, which is coarse, tapered, and has a hollow core of air filled with air.
Black hair of a human soaked in mineral oil and hair of an ICR mouse. Image source: Courtesy of the author
These small tubes in the center of the hair scatter and reflect light, giving polar bears' fur a white or yellowish appearance. This special structure allows polar bear fur to retain heat in extreme cold environments, while also helping to dry quickly after swimming.
In addition, these hollow tubes also make polar bears' hair very light, helping them reduce drag when swimming in the water.
Therefore, white fur does not mean that their hair is really white. And polar bears' skin is actually black, which can be clearly seen from their noses and mouths, which directly indicates that they are not albino species.
Copyright images in the gallery are not authorized to be reproduced
However, in the rapidly changing Arctic environment, white fur also poses a problem for polar bears. As sea ice shrinks, so does the natural habitat of polar bears. The disappearance of sea ice means less snow, which in turn makes the white fur of polar bears less effective at camouflage, making hunting more difficult.
Polar bear while swimming. Copyright images in the gallery are not authorized to be reproduced
What you may not know is that the "white" fur of polar bears is not always this color either. In some cases, it will appear yellow, brown, or even green. This discoloration is caused by the accumulation of algae and other microorganisms growing on the fur.
Although discoloration of the fur of polar bears is not common, they do not cause any harm to polar bears. In fact, chlorella and other microbes can help polar bears stay warm in extreme environments because they absorb sunlight and help polar bears maintain body temperature. In addition, these microorganisms can provide additional protection and reduce the risk of skin diseases and parasites in polar bears.
Copyright images in the gallery are not authorized to be reproduced
03
To protect polar bears, we are in action
Do you know? February 27 is International Polar Bear Day!
International Polar Bear Day was first launched in 2004 by Polar Bears International to raise awareness of the impact of global warming and human activities on polar bears.
And the date of Polar Bear Day was chosen for a special reason: February 27 is the birthday of Dr. Steven Amstrup, a famous American zoologist and polar bear conservation advocate. As a leader in polar bear conservation, he has made great contributions to the work of protecting polar bears.
Dr. Steven Amstrup. Image credit: Polar Bears International
Polar bears today face many threats, including climate change and human activity. The loss of sea ice means that their habitat and food sources are affected due to the loss of sea ice due to global warming, which they rely on to hunt seals and travel.
The protection of polar bears is an important part of the conservation of biodiversity, and reducing greenhouse gas emissions, reducing energy consumption and advocating environmental protection concepts will make positive contributions to the conservation of polar bears.
So, let's work together to protect these cute bears that have faded their "white halo"!
Produced by: Popular Science China
Author: Li Zhen (Institute of Zoology, Chinese Academy of Sciences)
Executive Producer: China Science Expo