Natures wonders: polar bears deicing method (Introduction)

by David Turell , Sunday, March 16, 2025, 19:02 (18 days ago) @ David Turell

A special chemical on the fur:

https://www.the-scientist.com/hair-oils-prevent-polar-bear-fur-from-freezing-up-72782

"...they analyzed the polar bear sebum’s composition to identify which components might be responsible for the oil’s ice resistance. Sebum is comprised of lipids and other hydrophobic and hydrophilic compounds that determine its physical properties. Using multiple analytical chemistry techniques, they found that the sebum was rich in glycerol species, waxes, and cholesterols, but was lacking in hydrocarbons, specifically squalene, a common component of sebum in other mammals.

"Using in silico modeling, the team assessed how these molecules interacted with ice molecules. They also investigated this for polyfluoroalkyl substances (PFAS) and squalene as comparisons.

"...they analyzed the polar bear sebum’s composition to identify which components might be responsible for the oil’s ice resistance. Sebum is comprised of lipids and other hydrophobic and hydrophilic compounds that determine its physical properties. Using multiple analytical chemistry techniques, they found that the sebum was rich in glycerol species, waxes, and cholesterols, but was lacking in hydrocarbons, specifically squalene, a common component of sebum in other mammals.

"Using in silico modeling, the team assessed how these molecules interacted with ice molecules. They also investigated this for polyfluoroalkyl substances (PFAS) and squalene as comparisons.

"They showed that diacyl glycerol species, cholesterols, and long chain fatty acids resisted adhering to ice comparably to PFAS, whereas squalene exhibited high ice adhesion. “[It was exciting] seeing how well polar bear hair oils did compared to the fluorocarbons, because they're very nasty chemicals,” Carolan said. Although PFAS have many useful properties, these compounds do not decompose in the environment or in animals that eat them, leading to accumulation that becomes toxic.

“'The most striking thing for me was just how effective the anti-icing property seemed to be,” said Whiteman, who was not involved with the study.

***

“'[Polar bears] are very different than grizzly bears,” Derocher said. For example, unlike polar bears, which he said remain dry down by their skin when they emerge from water, grizzly bears do not. “They're like a wet dog,” he added. “If grizzly bear hair either doesn't have as much of these oils, or they're constructed differently, that would give us a little bit more insight as what's going on.”

***

"While the team showed that polar bears resist icing through this chemical method, other animals, such as penguins, rely upon structural properties of their fur or feathers for ice resistance."

Comment: I wonder about diving birds in the Arctic and other animals who are partially aquatic in their lifestyles. The evolutionary process has a solution for every challenge.