How do elephants eat cereal? With a pinch

Author: Bethany Brookshire / Source: Science News for Students

an photo of an elephant holding its trunk to its mouth to eat some food — With their long, flexible noses, elephants can eat whole tree branches like they were stems of broccoli. But they use a newfound tactic to pick up tiny bits of food, scientists have just shown.

Never challenge an elephant to an eating contest.

A fully-grown elephant can down 200 kilograms (that’s 440 pounds) of greenery every day. It can snap off whole tree branches and munch on them like giant stalks of broccoli. But how do elephants keep up their eating pace when faced with smaller food pieces , such as a bowl of cereal? They simply press and pinch with their flexible trunks, a study now finds. This newfound tactic could guide engineers in designing better flexible robots.

David Hu usually focuses on the other end of an elephant. He is a mechanical engineer — someone who studies how things move. He works at the Georgia Institute of Technology in Atlanta. Hu and his colleagues had spent a lot of time at the Atlanta zoo taking videos of elephants from behind. Specifically, he notes, they studied “elephant peeing and pooping.” His lab had been comparing how quickly different animals get rid of their wastes.

But the other end of the elephant is interesting, too, pointed out a curator at the zoo. When Hu finally got a demonstration, he was impressed. “I’d never seen them eat anything,” he says. “When there’s lots to gather they’re very fast — I would almost say greedy.”

an animated gif showing how Kelly the elephant uses her trunk to grab bran cereal — This is Kelly eating bran cereal. Note how she presses and pinches her trunk back.

Hu’s team began to wonder how elephants used their trunks to gather different types of food. They were especially interested in how these animals picked up granular materials — things such as cereal, flour or sugar. “Granular material is anything made up of lots of smaller pieces,” explains Scott Franklin. He’s a physicist at the Rochester Institute of Technology in New York.

“Granular materials are between solids and liquids,” notes Karen Daniels. She’s a physicist at North Carolina State University in Raleigh and did not take part in the new study. Such materials behave unpredictably, she says. For example, when someone tries to pour cereal out of a box, it may get stuck. Bang on the box and a cereal avalanche suddenly overflows the bowl. Studying how other animals — such as elephants — lift weird materials might help engineers develop robots that can do the same thing.