Whether or not itтАЩs possible to teach an old elephant new tricks, a 34-year-old pachyderm at Zoo Atlanta has recently taught researchers a thing or two about how elephants suck up food and water with their trunks.
For one thing, an elephant doesnтАЩt use its trunk as a simple straw. It can also dilate its nostrils to boost its trunkтАЩs carrying capacity while snorting up water, researchers report online June 2 in the Journal of the Royal Society Interface. And that means it takes fewer snorts than expected to stock up on water that they use to drink and hose themselves down.
The surprise finding came courtesy of detailed measurements during feeding time, says Andrew Schulz, a mechanical engineer at the Georgia Tech in Atlanta. Other than aquatic creatures, not many animals other than elephants use a type of suction feeding that doesnтАЩt depend on lung power alone.
Elephants are the only living land animals to evolve a long, boneless appendage like a trunk, says Schulz. A septum stretching the length of the trunk separates it into two nostrils. But detailed knowledge of what happens inside that muscular structure during feeding has been sorely lacking. So Schulz and his colleagues worked with zookeepers at Zoo Atlanta to take a peek.
Using ultrasound to monitor what was happening inside the trunk during feeding, the researchers put one of the zooтАЩs African elephants through her paces during the summer of 2018. In some trials, the elephant snorted up volumes of water, which in some cases had bran mixed in.
To the researchersтАЩ surprise, says Schulz, the ultrasound revealed that each nostrilтАЩs available volume ballooned by as much as 64 percent, up from the trunkтАЩs original capacity of about five liters (although the elephant used only a small fraction of this extra space). Flow rate of water through the trunk averaged about 3.7 liters per second, or the equivalent of the amount of water pouring out of 24 shower heads at once.
In other trials, the elephant was offered small cubes of rutabaga of various sizes. When offered just a few cubes, the elephant picked them up with the prehensile tip of the trunk. But when offered piles of cubes, she switched into vacuum mode. Here, the nostrils donтАЩt expand, but rather the elephant breathes in deeply to hoover up the food.
Based on the amount and rate of water snuffed up by the elephant, the researchers estimated that airflow through the narrow nostrils could at times exceed 150 meters per second тАФ more than 30 times as fast as a human sneeze, Schulz says.
┬аThe internal structure of an elephantтАЩs trunk тАФ except for the nostrils тАФ is similar to an octopusтАЩs tentacle or a mammalian tongue, says William Kier, a biomechanicist at the University of North Carolina at Chapel Hill who was not involved with this study. The trunkтАЩs intricate musculature and lack of joints тАЬcreate a great diversity, complexity and precision of movement,тАЭ he says.
тАЬHow elephants use their trunks is pretty fascinating,тАЭ says John Hutchinson, a biomechanicist at the Royal Veterinary College in Hertfordshire, England, also not involved with this study (SN: 11/16/15). And although engineers have already designed robotic devices based on an elephantтАЩs trunk, the teamтАЩs new findings may yield even wilder designs, he says. тАЬYou never know where bioinspiration will lead.тАЭ