Research conducted by the Georgia Institute of Technology and Zoo Atlanta reveals that the skin on the elephant’s trunk does not stretch all the same , with the upper part being more flexible than the lower part. The lower part and the upper part begin to separate when the animal stretches 10% of the trunk. When the elephant stretches out its trunk to catch food or objects, the dorsal part slides forward.
The findings, published in the journal Proceedings of the National Academy of Sciences ( PNAS ), could serve to improve robots that are currently built either for great strength or for great flexibility, but not both. the time In this sense, the researchers refer to soft robotics , whose liquid-filled cavities allow for flexible movements, but break easily if a force is applied. The discovery of this function of the skin that was unknown could serve to use a similar structure that surrounds soft robotics and thus provide it with protection against force, but also flexibility.
“When people extend their tongue – a boneless, muscle-filled tissue similar in composition to an elephant’s trunk – it stretches evenly. We expected the same thing to happen when we challenged an elephant to reach for food.” explains Andrew Schulz, lead author of the study and a doctoral student at Georgia Tech’s George W. Woodruff School of Mechanical Engineering. He and his team filmed two African savanna elephants reaching for bran cubes and apples at the zoo Atlanta. “But when we looked at our high-speed camera images and traced the movements of the tube, we were surprised. The top and the bottom didn’t match up at all,” Schulz said.
After this, the researcher tried to stretch the skin of the trunk of a stuffed elephant to see what happened. What happened was that the upper part of the skin was 15% more flexible than the lower part . The team also realized that in the videos they were not only seeing the movement of the muscles of the tube but of a thick layer of skin.
“The flexible skin folds are the elephant’s innovation,” said David Hu, an adviser to Schulz and a professor at the Woodruff School and the School of Biological Sciences. “They protect the dorsal section and make it easier for the elephant to reach downwards, the most common gripping style when picking up objects.”
This research shows that the trunk of elephants works differently from other animal appendages that have muscles but not bones, such as the tentacles of octopuses and squids, because they do not extend evenly. The animal first extends the part that includes the tip of the trunk, then the adjacent area, later the next, and thus moves backwards towards it. According to Schulz, the progressive movement towards the base is intentional .
“Elephants are like people: they are lazy,” he says. “The section at the end of the trunk has a liter of muscle. The section closest to its mouth is 11 to 15 liters of muscle. An elephant will stretch the end of the trunk first and then the adjacent section, because they are easier to stretch.” move. If an elephant doesn’t have to work very hard to reach something, it won’t.”
Schulz is a mechanical engineer and part of his curiosity about elephants stems from his desire to help them. He believes that knowing them better will allow increasing efforts to conserve them. His role as a mechanical engineer makes him see applications in robotics. “Soft robotics created with biologically inspired design is always based on muscle movement. If wrapped with a protective skin, like an elephant’s trunk full of muscles, the machines could apply greater forces ,” he explains. “Last year we learned that the tube is a multipurpose muscular hydrostat. Now we know that the skin is another tool at its disposal.”
Referencia: Schulz, A., Boyle, M. et. al. 2022. Skin wrinkles and folds enable asymmetric stretch in the elephant trunk. PNAS. DOI: https://doi.org/10.1073/pnas.2122563119
