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Newly recognized tricks help elephants suck huge amounts of water

Whether or not it’s possible to teach new tricks to an old elephant, a 34-year-old pachyderm at the Atlanta Zoo recently taught researchers a thing or two about how elephants suck food and water with their trunks.

For one thing, an elephant doesn’t use its trunk like a simple straw. It can also dilate the nostrils to increase the carrying capacity of your trunk while sniffing water, the researchers report June 2 online in the Journal of the Royal Society Interface. And that means fewer puffs are needed than expected to stock up on water they use to drink and eat.

The surprise discovery was courtesy of detailed measurements during feeding time, says Andrew Schulz, a mechanical engineer at Georgia Tech in Atlanta. In addition to aquatic creatures, there are not many animals other than elephants that use a type of sucking feed that does not depend solely on lung power.

Elephants are the only living land animals to evolve a long boneless appendage like a trunk, Schulz says. A septum extending the length of the trunk separates it into two nostrils. But there was a lack of detailed knowledge of what happens within that muscle structure during feeding. So Schulz and his colleagues worked with guards at the Atlanta Zoo to take a look.

The trunk of an elephant is iconic. But it took a long time to understand what happens within that muscle structure during feeding. Experiments with a patient pacididerm at the Atlanta Zoo reveal their tricks for inhaling from small rutabaga buckets to large volumes of water.

Using ultrasound to monitor what was going on inside the trunk during feeding, investigators put one of the zoo’s African elephants in the summer of 2018. In some trials, the elephant snorted volumes of water, which in some cases mixed bran. inside.

To the researchers' surprise, Schulz says, the ultrasound revealed that the available volume of each nostril increased to 64 percent, above the original trunk capacity of about five liters (although the elephant used only a small fraction of this extra space) . The flow of water through the trunk averaged about 3.7 liters per second, or the equivalent of the amount of water poured from 24 shower heads at a time.

A layer of chia seeds along a container of water helped researchers study how quickly an African elephant sucks water from its trunk.A.K. Schulz et al / J. Roy. Soc. Interface 2021

In other trials they offered the elephant small cubes of rutabaga of various sizes. When offered a few buckets, the elephant grabbed them with the prehensile tip of the trunk. But when he was offered lots of buckets, he went into vacuum mode. Here, the nostrils do not expand, but the elephant breathes deeply to ruin the food.

Based on the amount and speed of water the elephant pulled out, the researchers estimated that the flow of air through the narrow nostrils could sometimes exceed 150 meters per second, more than 30 times faster than a human sneeze, says Schulz .

The internal structure of an elephant's trunk – except the nostrils – is similar to the tentacle of an octopus or the tongue of a mammal, says William Kier, a biomechanic at the University of North Carolina at Chapel Hill who did not participate in this study. The intricate musculature of the trunk and the lack of joints “create great diversity, complexity, and precision of movement,” he says.

“How elephants use their trunks is quite fascinating,” says John Hutchinson, a biomechanic at the Royal Veterinary College of Hertfordshire, England, who also did not participate in this study (SN: 16/11/15). And while engineers have already designed robotic devices based on an elephant’s trunk, the team’s new findings can result in even wilder designs, he says. "You never know where bioinspiration will lead."

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