In a groundbreaking discovery, scientists have unraveled the survival secrets of polar bears in extreme Arctic environments. The remarkable ability of polar bears to maintain warmth and dryness even after diving and hunting underwater has long captivated researchers. This newfound understanding not only deepens our knowledge of polar bear ecology but also holds promise for the development of innovative anti-icing coatings.
Polar bears, penguins, and other Arctic fauna thrive in environments with temperatures below -40°C, engaging in activities like diving for food and resting on snowy terrain. The resilience of these animals in such freezing conditions has long perplexed observers.
Previously, scientists attributed the insulation of polar bears to their blubber and fur layers but knew little about how exactly the fur functioned as an anti-icing barrier.
A team of researchers from Trinity College Dublin, Royal Society-Science Foundation Ireland University, and the University of Bergen discovered that the secret to the bear’s anti-icing prowess lies in the rich lipid content in their fur, making it difficult for frost to adhere. Their research findings were published in the journal “Science” on January 29th.
It has been observed that not only do polar bears possess remarkable insulation capabilities, but they can also effectively shed water by shaking themselves after swimming, roll in snow to freeze the remaining water, causing it to fall off their fur. Furthermore, the fur of polar bears is highly valued by indigenous Arctic peoples like the Inuit, who use it for various purposes such as laying on icy surfaces for still hunting, making non-slip covers for seats, and crafting footwear.
The scientific team conducted detailed examinations of polar bear hair and behavior to understand how these animals maintain warmth and dryness even after hunting underwater or frolicking in icy terrains.
They found that the fur of polar bears contains abundant “sebum,” which acts as a vital protective agent. This sebum, or hair oil, is rich in cholesterol, triglycerides (TG), diacylglycerols (DG), but lacks squalene, a compound found in the sebum of aquatic mammals and human skin.
Researchers further confirmed that the anti-icing, water-shedding, and ice-shedding abilities of squalene are far inferior to the sebum present in polar bear fur. Additionally, the performance of the anti-icing properties of arachidic acid and cholesterol in polar bear sebum is comparable to the commonly used waterproofing chemical substance perfluoroalkyl substances (PFAS).
The team conducted a series of tests on the overall anti-icing performance of polar bear fur. The results showed that the frost adhered to the fur could be easily removed with just a gentle breeze, surpassing the effectiveness of synthetic ski skins commonly used on skis.
Researchers indicated that this study has unveiled the secrets of polar bear fur, paving the way for the potential development of synthetic lipid mixtures similar to polar bear sebum for applications in anti-icing surface coatings and ski skins.
Furthermore, the study of polar bear fur has provided insights into the culture and lifestyle of the Inuit people, shedding light on why traditional practices involve using soapstone or dry clay to clean fox fur and other animal pelts, but not specifically grooming polar bear fur, as one is conducive to anti-icing, while the other is not.
Dr. Julian Carolan, a doctoral student at Trinity College Dublin’s Amber Research Center, the first author of the journal article, highlighted the significance of the study, stating, “We compared the anti-icing effects of polar bear hair, human hair, and two types of ski skins and found that the oily sebum on polar bear fur is the key to anti-icing, as the greasy fur makes it challenging for ice to adhere.”
She added, “However, once we washed the polar bear hair clean, ice easily stuck to it, similar to human hair. Additionally, human hair, whether washed or not, readily freezes.”
Dr. Richard Hobbs, a senior author of the journal article affiliated with the Royal Society-Science Foundation Ireland University, Trinity College Dublin, and Amber Research Center, emphasized the inspiration drawn from polar animals residing in polar regions in the development of new anti-icing materials. He highlighted that understanding the natural lipids of polar bears would aid in developing alternative anti-icing coatings to replace PFAS.