It has more peculiarities than one imagines. It can do heavy work and other very light and delicate jobs. The elephant’s versatile trunk holds some secrets. A study from the Georgia Institute of Technology (USA) reveals them. The article was published in ‘Proceedings of the National Academy of Sciences’ (PNAS).
Andrew Schulz and his team filmed two elephants foraging for food at Zoo Atlanta. “We looked at the images on our high-speed camera. As we traced the movements of the trunk, we were surprised. The top and bottom were not the same at all,” he notes.
Next, they stretched tissue from a dissected elephant to better understand the elasticity of the skin. It was found that the skin does not stretch uniformly. The upper part of the trunk is 15% more flexible than the lower part. And that asymmetrical stretching is due in part to differences in skin wrinkling patterns. When stretching to reach for food or objects, the dorsal section of the trunk slides more forward.
“Flexible skin folds are the elephant’s innovation,” says David Hu. He is a professor in the School of Biological Sciences. “They protect the dorsal section and make it easier for the elephant to bend downward. It’s the most common gripping style when picking up objects.”
The versatile elephant trunk does not extend evenly. It stretches telescopically like an umbrella, gradually lengthening in waves. An elephant first extends the section that includes the tip of its trunk. Then the adjacent section, and so on. The progressive movement toward the base is intentional.
As a mechanical engineer, Schulz also sees the applications of these findings in robotics. There, methods are required that provide great strength or great flexibility. Unlike an elephant’s trunk, the machines cannot do both. “Soft robotics created with a biologically inspired design are based on muscular movements. What if they were wrapped with a protective skin, like an elephant’s trunk? The machines would be able to apply larger forces,” he says.