Ice crystals can’t keep on with polar bear fur
Ondrej Prosicky/Shutterstock
Polar bears have a hidden-in-a-plain-sight superpower that anybody who has watched a wildlife documentary might have noticed: ice doesn’t keep on with their fur.
This has lengthy been recognized to Indigenous peoples of the Arctic, who’ve utilised this property of the fur, however solely now has it been seen and studied by scientists. Bodil Holst on the College of Bergen in Norway and her colleagues have proven that the ice resistance of polar bear fur is because of pure oils secreted onto the hairs, somewhat than a property of the fur itself.
Holst is a physicist who research the properties of surfaces. Her curiosity in polar bear fur started when, whereas watching a TV quiz programme, she noticed that the bears barely present up on infrared cameras as a result of they’re so properly insulated. Which means the temperature of their outer fur is under freezing, Holst realised, however she had by no means seen a polar bear in wildlife movies that was coated with ice, even after swimming in sub-zero waters.
“After which I assumed, properly, how come freezing will not be an issue? How come you don’t get accumulation of ice on the fur below these circumstances?” she says.
That is, in any case, an issue for a lot of different land mammals in chilly environments, from musk ox to bearded polar explorers. Holst requested researchers on the Norwegian Polar Institute in the event that they knew why polar bear fur doesn’t ice up. None did, however they determined to analyze collectively.
Holst and her colleagues obtained samples of polar bear fur from Svalbard in Norway and in contrast them with human hair. They discovered that the power required to take away ice from polar bear hair was 1 / 4 of what was wanted for human hair – that means the bears can simply shake any ice off.
Washing polar bear fur eliminated its ice resistance, suggesting that the oily coating on the hairs is the important thing to its properties. This substance, often known as sebum, is secreted by glands related to hair follicles.
Polar bear sebum lacks a substance referred to as squalene that’s generally present in sebum, particularly in aquatic mammals, the workforce discovered. It additionally comprises some uncommon fatty acids. These could possibly be distinctive to polar bears, however we are able to’t ensure of that, as so few research have seemed on the composition of animal sebum, says Holst.
Arctic peoples such because the Inuit have historically ready polar bear fur in a method that preserves the sebum, not like strategies used for different furs. They’ve additionally used the fur in ways in which make use of its ice-resistant properties.
For example, Inuit hunters in Greenland are recognized to have positioned small items of polar bear fur below the legs of the stools utilized by hunters, to cease them sticking to ice. Additionally they strapped polar bear fur to the soles of trainers whereas stalking animals, to keep away from the noise made by ice-coated surfaces.
Holst’s workforce is now exploring potential purposes, corresponding to creating environmentally pleasant ski waxes that don’t include the long-lasting fluorocarbon compounds at the moment used to stop icing.
A hair wax based mostly on polar bear sebum might additionally assist individuals who work in chilly environments. “I had not thought of that utility, however completely, that ought to work,” says Holst. “I feel you’ve simply given me a brand new concept.”
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