Tremendous Trunks

When Andrew Schulz was a teenager, he visited Africa with his mother. While there, he fell in love with elephants. He was especially intrigued by the enormous animals’ most famous feature: their trunks. Elephants use their long, flexible noses to breathe, grasp food, and even suck up water.

Today, Schulz is a Ph.D. student at the Georgia Institute of Technology, where he is studying mechanical engineering. Inspired by his fondness for elephants, he decided to learn more about the biomechanics of their trunks. Biomechanics is the study of how living things move. Schulz was particularly curious about how the huge mammals use their trunks to eat. “It’s one of those things you always see, but no one really knows what’s going on,” he says.

When Andrew Schulz was a teenager, he visited Africa with his mother. That’s when he fell in love with elephants. He was especially interested in the huge animals’ most famous feature: the trunk. Elephants use their long, flexible noses to breathe, grab food, and even transport water.

Today, Schulz is a Ph.D. student at the Georgia Institute of Technology. He’s studying mechanical engineering. His love for elephants inspired him to learn more about the biomechanics of their trunks. Biomechanics is the study of how living things move. Schulz wondered how the huge mammals use their trunks to eat. “It’s one of those things you always see, but no one really knows what’s going on,” he says.

In 2018, Schulz performed a series of experiments with a 34-year-old African elephant named Kelly at Zoo Atlanta in Georgia. During his investigation, he discovered something surprising: Elephants don’t use their trunks just to grab food and carry it to their mouths. They also use their trunks to suction up tasty treats.

In 2018, Schulz did some experiments with a 34-year-old African elephant named Kelly. She lives at Zoo Atlanta in Georgia. His experiments turned up a surprise: Elephants don’t use their trunks just to grab food and carry it to their mouths. They also use suction to pick up and eat some tasty treats. 

An adult elephant’s trunk is about 2 meters (6.6 feet) long, weighs 100 kilograms (220 pounds), and is made of mostly muscle, with no bones or joints. It might not seem like this long, heavy, muscular appendage would be all that agile. But elephants can control their trunks with great accuracy. Even though an elephant’s trunk is strong enough to uproot a tree and throw off an attacking lion, it’s nimble enough to pick up tiny seeds (see Trunk Tricks, below).

An adult elephant’s trunk is about 2 meters (6.6 feet) long and weighs 100 kilograms (220 pounds). It’s made mostly of muscle, with no bones or joints. Since the trunk is long and heavy, it might seem difficult to use. But elephants can control their trunks with great accuracy. An elephant’s trunk is strong enough to uproot a tree and throw off an attacking lion. And it’s nimble enough to pick up tiny seeds (see Trunk Tricks).

Until recently, though, no one really understood how the biomechanics of an elephant’s trunk allowed it to manage these feats. “The only information we had about its structure was a hand drawing from 1908,” says Schulz.

He and his team wanted to find out more about how elephants use their trunks to eat. They set up slowmotion video cameras to record how Kelly the elephant ate. The team fed Kelly cubes of rutabaga, a turniplike root vegetable. When given a large chunk, Kelly would lift it with her trunk’s two “fingers”—projections at the tip of the trunk that an elephant uses to grasp objects. But when given many small pieces, Kelly would gather them all together, suck the bits up into the tip of her trunk, and then shoot them into her mouth. As far as Schulz knows, that was the first time anyone had observed an elephant using suction to eat.

How do the biomechanics of an elephant’s trunk allow it to achieve these feats? No one really understood until recently. “The only information we had about its structure was a hand drawing from 1908,” says Schulz.

He and his team wanted to learn how elephants use their trunks to eat. So they set up slow-motion video cameras. Then they recorded how Kelly the elephant ate. The team fed Kelly cubes of rutabaga. That’s a root vegetable like a turnip. When they gave Kelly a big chunk, she would lift it with her trunk’s two “fingers.” These extend from the tip of the trunk. An elephant uses them to grab objects. But when they gave her many small pieces, Kelly would gather them all together. She would suck the bits up into the tip of her trunk, and then shoot them into her mouth. Schulz believes that was the first time anyone observed an elephant using suction to eat.

Schulz wanted to give Kelly another challenge: How might she handle eating a delicate, flat object, like a leaf on the ground? The team decided to test Kelly using a large, round tortilla chip. If you’ve ever dropped a penny on the floor and tried to pick it up, you’ve probably noticed it can be hard to grab. Now imagine having to pick it up with your nose! Not only that, a tortilla chip breaks easily.

Kelly first tried using her trunk to grab the chip, but she quickly sensed that it was too fragile. Then, to the team’s surprise, she hovered the end of her trunk above the chip and tried sucking it up. The suction wasn’t powerful enough, though. So she pressed her trunk lightly onto the surface of the chip and sucked again. The snack stuck! She transported the chip on the end of her trunk to her mouth and—CRUNCH!

Schulz wanted to give Kelly another challenge. How might she eat a delicate, flat object, like a leaf on the ground? The team decided to test her. They used a large, round tortilla chip. Have you ever dropped a penny on the floor and tried to pick it up? You probably know it can be hard to grab. What if you had to pick it up with your nose? Plus a tortilla chip breaks easily.

First, Kelly tried to grab the chip with her trunk. But she quickly sensed that it might break. Then she did something that surprised the team. She held the end of her trunk above the chip and tried to suck it up. But the suction wasn’t powerful enough. So she pressed her trunk lightly onto the chip and sucked again. The snack stuck! She carried the chip on the end of her trunk to her mouth and—CRUNCH!

Before the experiment with Kelly, scientists didn’t realize elephants used their trunks to suck up food. But they did know that elephants used them to slurp up water. “People think a trunk is like a drinking straw,” says Schulz. “But it’s really more like a ‘trunk’ for storage.” Elephants don’t sip water through their noses. They instead use them to collect the liquid—as much as 5.5 liters (1.5 gallons)—and then shoot it into their mouths.

To learn how elephants create that suction and how strong it can be, Schulz’s team set up a large aquarium. Schulz measured the rate at which Kelly sucked up the water inside the tank. They found that in just 1.5 seconds, Kelly could suck up 3.7 liters (1 gallon). “It’s absolutely insane!” says Schulz.

Before the experiment with Kelly, scientists didn’t know elephants sucked up food with their trunks. But they did know that elephants sucked up water with them. “People think a trunk is like a drinking straw,” says Schulz. “But it’s really more like a ‘trunk’ for storage.” Elephants don’t sip water through their noses. Instead, they use them to collect the liquid and shoot it into their mouths. A trunk can hold as much as 5.5 liters (1.5 gallons).

Schulz’s team wanted to learn how elephants create that suction and how strong it can be. So they set up a large aquarium. Schulz measured how fast Kelly sucked up the water inside the tank. They found that she could take in 3.7 liters (1 gallon) in just 1.5 seconds. “It’s absolutely insane!” says Schulz.

Schulz’s group then looked at slow-motion video of Kelly drinking. With help from zoo veterinarians, they also used an ultrasound device to create an image of the inside of Kelly’s trunk. As Kelly sucked up water, they could see her two nostrils dilate, or open wider. Her nostrils, which span the length of her trunk, increased in volume by 64 percent. “It’s like when you use a straw,” explains Schulz. “You’re going to be able to suck up more liquid with a wider one.”

Schulz’s investigation didn’t just uncover one of the biomechanical mysteries of elephants’ trunks. His findings could have other applications as well. One example, says Schulz, is to build better robots that, like elephants, use a combination of grasping and suction to pick up objects.

Then Schulz’s group watched slow-motion video of Kelly drinking. Zoo veterinarians also helped them use an ultrasound device to create an image of the inside of Kelly’s trunk. Kelly’s two nostrils are as long as her trunk. As she sucked up water, the team saw her nostrils dilate. They opened wider and increased 64 percent in volume. “It’s like when you use a straw,” explains Schulz. “You’re going to be able to suck up more liquid with a wider one.”

Schulz’s experiments uncovered one of the biomechanical mysteries of elephants’ trunks. But his findings could also have other uses. One example is to help engineers build better robots, says Schulz. Like elephants, robots would use both grabbing and suction to pick up objects.