Saturday, January 20, 2024

Design Principles: Polar Bear Paws

Environmental & Science Education, STEM, Nature, Wildlife, Biodiversity, Biological Evolution, Maths, Models

Ed Hessler

You may have wondered how polar bears avoid slipping and sliding when they are on the ice. It had never occurred to me, even when I watched them swimming in our local zoo. My attention was always on the size of their paw pads.

Well, it turns out I was wrong about the size of their paw pads. They are smaller when compared to other species.

Austin M. Garner (Syracuse University) and two others recently published a paper - it is technical but I'm going to refer you to some illustrations - in the Journal of the Royal Society Interface on how polar bear design principles help improve traction. I probably would never have been able to get close enough to the paws when it was pressing against the plate glass to make a turn to notice the papillae on the footpads, an event which happened very quickly.

The papillae are taller than than on other species - up to 1.5 times. This gives the bears advantages--grip and traction. In an SU press release by Dan Bernardi ** about research on polar bear design principles by Austin Garner, he begins by calling attention to the larger purpose of such science.

"Using the solutions observed in nature to address global challenges in health, medicine and materials innovation is at the heart of research by Bioinspired Syracuse *.  Austin Garner* is a member of Bioinspired who specializes in functional morphology—studying the form and function of animals and then applying it to bio-inspired designs in a wide range of applications." His interests are in how animals attach to surfaces in variable environments. * (Linked in press release).

Austin then introduces us to the team, how they did their research and its possible uses. You may be tempted as I was to think of this as an adaptation. Garner explains. “This is exciting interdisciplinary work that studied a long-held belief that the micro-structures on polar bear paw pads were an adaptation to increase traction on ice and snow. Our work shows that the papillae themselves are not an adaptation for this because other bears have them, but the unique dimensions of polar bear papillae do confer an advantage in traction.” "May be an adaptation" is as close as the authors are willing to get based on the evidence.

There is a link to the fully available technical report. I point out a few sections that may be of interest: the abstract, introduction, summary and conclusion. Throughout you will find photographs and graphs which help immensely. 
Please read the Ethics section at the end. "No animals were harmed or euthanized for the purposes of this study." This is followed by an explanation of the provenance of the paw materials used.

I was interested that the Goodyear Tire and Rubber Company provided fellowship support. This company has a natural interest in improving their products.  And there is also a section on the author's contributions.

** I also acknowledge that I used some material from a short article from Syracuse University Arts & Science, Fall 2023. Thanks.

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