Some animals transform their hair structure to battle winters

How do animals survive when the mercury drops far below what we can withstand? For some, the answer lies in an extraordinary feature – hollow hairs that provide remarkable insulation. These tiny structures, invisible to the naked eye, hold the key to endure the relentless onslaught of winter.

While most scientists understand the basics of hollow hairs, major research has centered on domesticated animals. The mysteries of hollow hair in wild animals, especially their seasonal transformations, remain an intriguing frontier.

A team at Utah Tech University is changing that, and their research sheds new light on how wild animals survive the challenges of winter.

Scanning electron microscope

Led by Professor Wendy Schatzberg and Professor Samuel Tobler, the team used a scanning electron microscope (SEM) to delve into the unseen world of animal hair. The project was led by undergraduate student Taylor Millett, driven by her love of the outdoors.

Millet meticulously examined hairs from three iconic big game animals: pronghorn antelope, mule deer, and Rocky Mountain elk. Under the SEM’s intense gaze, she discovered an intricate system resembling a messy honeycomb – a network of tiny air pockets.

The most striking revelation was that the honeycomb structure changes dramatically between summer and winter.

Seasonal transformations of animal hair

Summer hair exhibits a denser core with smaller air pockets. But when the chill descends, the structure transforms: all three species display winter hair with significantly larger air pockets.

To illustrate this, the average diameter of winter air pockets in mule deer measured 26 micrometers, which is double the size of their summer counterparts at 13 micrometers.

“This is very intriguing, because those pockets create an insulative barrier that keeps the animals warm in winter,” said Millett.

The power of insulation

“With some animals, the coat looks different in summer and winter,” explained Millett. “But in the animals we’re studying, we’ve found that it’s not just the outer coloring of the hair that’s changing. The inner microscopic details are also changing to allow these animals to continue surviving in their environment.”

The animal kingdom adapts by modifying the very structure of their hair to harness the insulating power of air. Why air, you might wonder?

Air is a notoriously poor conductor of heat. This property makes it an excellent insulator, a fact well known to anyone who has donned a down jacket on a cold day.

The principle at work is simple: trap air, and you trap heat. Animals with the ability to change their hair structure exploit this principle to its fullest, creating a natural, built-in barrier against the cold.

Biomimicry of animal hair: Houses and camping

The discovery’s impact stretches far beyond the realm of pure science. Engineers and designers can develop innovative synthetic materials inspired by these adaptations. “One potential application is synthetic insulation for houses and camping gear,” said Millett.

Imagine home insulation that’s both more effective and significantly lighter than current options. Instead of relying on bulky, environmentally-taxing materials, we could mimic the air-trapping structure of hollow hair to achieve superior insulation.

Furthermore, improved camping gear that offers excellent thermal protection would transform outdoor adventures. This biomimetic approach could make exploring nature more accessible and comfortable, even during colder seasons.

Future directions

Fueled by their findings, the team aims to expand its research horizons. They plan to collaborate with zoos around the world to investigate whether their discovery extends to other animals and how factors like geographic location and climate affect hollow hair.

“Is it just our area that’s like this? And how much temperature difference between the seasons does it take?” said Schatzberg.

This research demonstrates that the natural world is a treasure trove of innovation, waiting to be discovered.

Visit the ACS Spring 2024 program to learn more about this presentation, “Hollow hair and how its structure helps big game animals thermoregulate.”

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