The Intriguing Properties of Polar Bear Fur Lipids
- TRI Princeton
- Dec 16, 2025
- 3 min read
THE INTRIGUING PROPERITES OF POLAR BEAR FUR LIPIDS
Researchers from the University of Surrey, UK, have published research in Science Advances that reveals how polar bear (Ursus maritimus) fur can resist the formation of ice in extreme cold – and it’s all down to the mixture of lipids on the bear’s fur.
In the wild, polar bears live in one of the coldest climates in the world, where air temperatures can drop to –40 °C. The surface temperature of the fur is often close to the air temperature, and despite the cold, it’s regularly observed that their fur is typically free of water and ice accumulation, even though polar bears spend significant time diving and swimming in the icy Arctic waters. While many studies have considered the thermal, structural and optical properties of polar bear fur, the anti-icing characteristics have not been probed.
In this work, the researchers suspected that the polar bear sebum was key to the anti-icing characteristics; therefore, they sought to both characterise the lipids in bear sebum collected from wild bears, as well as measure the ice adhesion strength, hydrophobicity and freezing-delay times of water on the fur fibers.
Analysis of wild polar bear sebum content was completed through the use of GC-MS, LC-MS/MS and NMR, all of which are also available as testing techniques at TRI Princeton. Overall, it was shown that waxes and glycerol species constituted the bulk of the lipids in the sebum, with an abundance of eicosanoic acid and cholest-5-en-3β-ol. However, a lack of squalene, a key component of sebum in many aquatic mammals, was observed. This finding was key, as squalene has been found to provide surfaces with higher friction. In the case of the polar bear, it’s likely that a biosynthetic conversion of squalene into cholest-5-en-3β-ol occurs. It’s known that cholest-5-en-3β-ol considerably reduces surface friction of materials, and also lowers the ice adsorption energy, meaning any ice formed on the surface is more easily removed. Furthermore, the lipids in polar bear sebum contain a high degree of unsaturation, more methyl-branching and long carbon chains in the fatty acids when compared with other species, which may also contribute to the anti-icing properties, although further investigation is required.
Comparisons between human hair, which is high in squalene and structurally similar to polar bear hair, and polar bear fur were also undertaken. It was shown that without sebum, there was minimal difference in hydrophobicity between polar bear and human hair – both displayed strong adhesion to ice – as well as the freezing time for water once on the hair fiber surface. Fibers coated in squalene also gave strong adhesion to ice. This further reiterated that the composition of the polar bear sebum, in particular the absence of squalene, was essential for its anti-icing properties.
Finally, alongside the chemical composition of the sebum, the impact of sebum removal was also investigated. When the sebum was removed, ice adhesion strength to the hair fibers increased fourfold, proving that the sebum was essential for the de-icing performance.
This research is likely of interest to those looking to develop anti-icing products within materials science, as well as those working within hair care who may be looking to develop formulations that avoid hydration of hair fibers, for example, after styling or to prevent frizz and flyaway.
