According to a new study, an elephant's folded skin plays an important role in stretching its trunk in addition to its muscles. The combination of muscle and skin allows the animal to grasp delicate vegetation and rip tree trunks apart. According to the findings, an elephant's skin does not stretch uniformly. The top of the trunk is more flexible than the bottom, and when an elephant reaches more than 10%, the two sections begin to diverge. When reaching for food or objects, the trunk's dorsal section slides forward.
According to a new study from the Georgia Institute of Technology, an elephant's folded skin plays an important role in stretching its trunk in addition to its muscles. The combination of muscle and skin allows the animal to grasp delicate vegetation and rip tree trunks apart.
The study, conducted in collaboration with Zoo Atlanta, discovered that an elephant's skin does not stretch uniformly. The top of the trunk is more flexible than the bottom, and when an elephant reaches more than 10%, the two sections begin to diverge. When reaching for food or objects, the trunk's dorsal section slides forward.
The findings have the potential to improve robotics, which is currently designed for either extreme strength or extreme flexibility. The machines, unlike an elephant's trunk, cannot do both.
The authors of the study use soft robotics as an example. Their fluid-filled cavities allow for flexible movement but easily break when forced. According to the researchers, the elephant findings suggest that wrapping soft robotics with a skin-like structure could provide protection and strength while maintaining flexibility.
The paper was published in the Proceedings of the National Academy of Sciences (PNAS) by the same Georgia Tech team that discovered how elephants used their trunk muscles to inhale food and water last summer.
"When people stretch their tongue, which is a muscle-filled, boneless tissue similar to an elephant's trunk, it stretches uniformly. When we challenged an elephant to reach for food, we expected the same result "said Andrew Schulz, a Ph.D. student at Georgia Tech's George W. Woodruff School of Mechanical Engineering and the study's lead author. At Zoo Atlanta, he and his colleagues captured two African savanna elephants reaching for bran cubes and apples.
"We were surprised, however, when we examined our high-speed camera footage and plotted the trunk's movements. The top and bottom were not at all the same "Schulz stated.
Schulz stretched the tissue of a dissected elephant after seeing the video to better understand the skin's elasticity. That's when he discovered that the folded top of the skin is 15% more flexible than the wrinkled bottom side. It was also at this point that the team realized they weren't simply seeing muscle movement on the video. They were also following a thick layer of skin.
"The elephant's innovation is flexible skin folds," said David Hu, Schulz's advisor and a professor in the Woodruff School and the School of Biological Sciences. "They protect the dorsal section and allow the elephant to reach downward more easily, which is the most common gripping style when picking up items."
The Georgia Tech study discovered that an elephant trunk differs from other boneless, muscle-filled appendages found in nature, such as squid and octopus tentacles, in another way. An elephant's trunk telescopically stretches like an umbrella, gradually lengthening in waves, rather than extending evenly.
An elephant extends the section of its trunk that includes the tip of its trunk first, then the adjacent section, and so on, gradually working its way back toward its body. Schulz claims that the progressive shift toward the base is deliberate.
"Elephants, like people, are lazy," he explained. "One liter of muscle is contained in the section at the end of the trunk. The area closest to its mouth contains 11-15 liters of muscle. Because they are easier to move, an elephant will stretch the end of its trunk first, followed by the adjacent section. If an elephant does not have to exert much effort to reach something, it will not."
When learning about trunk anatomy, Schulz said he had to rely on a drawing from 1908 because scientists and engineers haven't done much research on elephant biomechanics in the last century. Part of his fascination with elephants stems from a desire to help them; he believes that a better understanding of the animals will lead to more effective conservation efforts. Schulz, a mechanical engineer, sees robotics applications.
"Soft robotics that is designed biologically are always based on muscle movement. The machines could apply greater forces if they were wrapped in a protective skin, similar to an elephant's muscle-filled trunk "He stated. "We discovered last year that a trunk is a multi-purpose, muscular hydrostat. We now know that skin is an additional tool at its disposal."
Reference DOI: 10.1073/pnas.2122563119