Snake miniatures reveal mysteries about sidesteps and slips

The dramatic flow of flanks moving suddenly over desert sands has captured biologists for centuries and has been studied over the years, but there were still questions about how the snakes take their lives. -out the unparalleled movement. Sidewinders are pit pipers, especially rattlesnakes, native to the deserts of the southwestern United States and nearby Mexico.

Scientists had already described the microstructure of the skin on the ventral surface, or abdomen, of snakes. Many of the snakes studied, including all species of piper, had specific “microspicules” (micron-sized protrusions on plates) that were described in the context of fracture reduction in the t. -way forward – the side where the snake was slicing – and increase friction in the back side to reduce slope.

Considered through a lens of a specific lateral locwinder shape, however, it appeared that these microspicules would not function in the same way. But no one had studied the microstructure of sidewinders, or a handful of unrelated African vipers that are also sideways.

Working with natural shed skin collected from snakes in a zoo, researchers used an atomic force microscope to see the microstructures of these scale protrusions in three species of sidewinding vipers as well as many other viper species for comparison. The results of the research, published this week in the journal Proceedings of the National Academy of Sciences, in fact the sides have a distinct structure rather than other snakes.

The microspicules were absent in the African sidewinding genus and reduced to tiny nubbins in the North American side. Special crater-like miniatures in the three snakes also produced a unique texture not seen in other snakes.

Daniel Goldman, Dunn’s Family Professor of Physics at Georgia Institute of Technology, and Jennifer Rieser, developed as a postgraduate researcher in the Goldman group and currently an assistant professor in the Department of Physics at Emory University , mathematical models to test how the normal texture of microspicules is directed behind it and the action of a spicule-free texture as snakes interact with the ground. The models showed that the microspicules would indeed inhibit laterality, explaining the evolutionary loss in these species.

The models also showed an unexpected result that microspicules work to enhance the performance of snakes using lateral movement. Lateral rotation is the standard side-to-side movement that is used by most snake species. “This discovery adds a new dimension to our knowledge of the potential of these structures, which is more complex than previous assumptions,” said Joseph Mendelson, research director at Zoo Atlanta and associate professor. in Georgia Tech School of Biological Sciences.

The models show that the microspicules function something like a corduroy cloth. “Anti-friction is low when you run your finger the length of the fur coat – consistent with previous work – but the grooves produce a great counter-movement when you move your finger on each over the texture of the fabric, “Goldman said. The potential of the special pits remains a mystery.

The findings could be important for the development of future generations of robots capable of moving over a challenging surface such as loose sand. “Understanding how and why this example of convergent evolution could allow us to adapt to our own needs, such as building robots that can move in challenging environments,” said Rieser.

In terms of anatomy, this was a classic example of convergent evolution between a pair of snake species in Africa and a closely related snake in North America, Mendelson noted. A biogeographic reconstruction by Jessica Tingle, a doctoral student at the University of California Riverside, indicated that African snakes are substantially older than the North American side, suggesting that the side snails represented an earlier stage. in adjustment for sideways.

Tai-De Li, then at Georgia Tech in the lab of Professor Elisa Riedo and now at New York City University, performed the AFM measurements.

Drawing from the fields of evolutionary biology, living systems physics, and mathematical modeling, the team conducted a study that explains some aspects of what these microstructures on snake bellies do and how they came to be forward in snakes.

“Our results highlight how an integrated approach can provide qualitative prediction for functional-structural relationships and insights into behavioral changes and evolution in biological systems,” the authors wrote. .

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This research was supported by the Georgia Tech Fund Elizabeth Smithgall Watts; PHY-1205878 and PHY-1150760 Institute of Science Living Systems Physics Grants; and Army Investigation Office Grant W911NF-11-1-0514. The opinions, conclusions, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the organizations that support them. .

CITATION: Jennifer M. Rieser, Tai-De Li, Jessica L. Tingle, Daniel I. Goldman, and Joseph R. Mendelson III, “The effect of the action of concomitantly developed microscopic skin features on snake movement.” (Proceedings of the National Academy of Sciences, 2021)