A dune of shifting sand in the Namib Desert isn’t the easiest place to get around. Just ask Solvin Zankl, the intrepid wildlife photographer who captured this image of a Peringuey’s adder (Bitis peringueyi) and its telltale tracks. Mid-day temperatures here can climb to 42 degrees Celsius (108 degrees Fahrenheit); cover consists of little more than parched tussocks of grass; and travel across this landscape—at least for humans—can literally be two steps forward, one step back. As the photographer sank and struggled through the loose sand, the snake seemed to float effortlessly across the surface at high speed. Its secret: sidewinding.
Snakes typically move through an environment nose-first. By rhythmically lengthening and contracting their muscle fibers, they cause their long bodies to undulate, pushing against surfaces with each movement to propel themselves forward. While this form of locomotion works well on firm ground with ample traction, it’s all but worthless in loose sand. For conditions like these, snakes have evolved another strategy for covering ground quickly. Sidewinding, as the term suggests, is a form of locomotion that moves a snake sideways along a path that’s diagonal to the length of its body. The linear tracks the snake leaves behind seem to suggest that the legless creature is somehow able to pick itself up and set itself off to the side, a few inches closer to where it wants to go. And in a sense, it does.
In a recent study, a team of scientists from the Georgia Institute of Technology and Carnegie Mellon University placed North American sidewinder rattlesnakes (Crotalus cerastes) on a loose sandy slope and filmed their movements from multiple angles using high-speed video cameras. The researchers found that a snake undulates simultaneously along two separate planes, moving both horizontally and vertically. At any point during the journey, only two parts of the snake’s body are in contact with the sand, while the rest is thrust in the direction the animal wants to go. This may sound inefficient, but it’s actually incredibly fast. Sidewinders have clocked in at speeds of 29 kilometers (18 miles) per hour, faster than the average human running pace.
Interestingly, the Peringuey’s adder doesn’t use sidewinding to chase down its prey. More often it performs this feat to escape predators, or to move quickly from one hideout to another while minimizing exposure to the hot sand on the dune’s surface. As an ambush predator, the reptile spends the majority of its time buried up to its eyes in the sand, waiting for prey. Although the snake is small—just 20 to 25 centimeters (8 to 10 inches) on average—it packs a swift and lethal strike for any hapless lizard that happens to blunder within its grasp.
Namib Desert, Namibia
Solvin Zankl has been working as a professional photographer since 1998. He is particularly interested in capturing the behaviors and unique characteristics of his subjects, and is known for his fresh perspectives of small and often overlooked species. You can see more of his work at solvinzankl.com.