On a sunny day at Zoo Atlanta in 2020, Kelly the African bush elephant reached for a snack and revealed one thing unusual.
High-speed cameras monitoring her actions instructed that the pores and skin on high of Kelly’s trunk stretched greater than the pores and skin beneath. “But that didn’t make any sense,” says Andrew Schulz, a mechanical engineer at Georgia Tech in Atlanta.
Scientists had assumed that elephant trunk pores and skin largely stretches the identical manner throughout. When Schulz despatched knowledge from Kelly and a male elephant, Msholo, to colleagues, they mentioned, “Oh yeah, your data is wrong,” he remembers.
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Follow-up experiments stretching items of elephant pores and skin within the lab confirmed the identical peculiar phenomenon: The pores and skin on the highest and backside of the trunk are two completely completely different beasts. “Talk about a great day as a scientist!” Schulz says. “That’s when we really started to believe that what we were saying was true.”
The robust higher pores and skin of an elephant’s trunk, which crumples into creases and crags just like the folded furrows of a shar-pei pet, is about 15 % stretchier than the gently wrinkled pores and skin on the underside, Schulz and his colleagues report July 18 within the Proceedings of the National Academy of Sciences.
When an elephant elongates its trunk, the higher pores and skin stretches greater than the pores and skin on the underside. Green crosses signify preliminary positions on the pores and skin. As the trunk extends, the crosses flip crimson and transfer to the fitting, indicating how a lot the pores and skin stretched.
That additional stretch in all probability helps elephants attain down and wrap their trunks round a log or a tree department, whereas the wrinkled pores and skin beneath provides the animals a great grip, Schulz says.
The group additionally noticed that the trunk extends like a telescope, the tip reaching out first, adopted by sections farther up. And on the trunk tip, it’s the pores and skin that does a lot of the straining, not the muscle, mathematical modeling experiments counsel.
Scientists have lengthy studied the muscle mass in elephant trunks (SN: 3/26/88). But pores and skin has largely been neglected, says Lucia Beccai, a delicate roboticist on the Italian Institute of Technology in Genoa who wasn’t concerned within the analysis. The new examine “tells us that the structure of elephant skin is not all the same.”
Artificial pores and skin is usually modeled after human pores and skin, however researchers might study so much from different animals, Beccai says. Understanding how Kelly’s and Msholo’s folds and wrinkles stretch is “surely information that will improve the design of soft robots,” she says.
