An elephant’s trunk is a miracle of biology. Without any joints or bones, the trunk is an appendage made of pure muscle that can both uproot trees and gently pluck individual leaves and also has a stronger sense of smell than that of a bomb sniffing dog.
Elephants use their trunks in different ways. They use it to drink, store, and spray water, and they also blow air through it to communicate – their 110 decibel bellows can be heard for miles.
“It’s like a muscular multitool,” says Andrew Schulz, a graduate student in mechanical engineering at the Georgia Institute of Technology.
In a study published Wednesday in the Journal of the Royal Society Interface, Mr Schulz and his colleagues reported on how elephants can use their trunks for another function: suckling to grab food, a behavior previously restricted to fish.
Despite the ubiquity of elephants in children’s books and nature documentaries, there are numerous scientific gaps in knowledge about the biomechanics of their trunks that are filled with the new study. For example, the latest detailed account of the anatomy of the elephant’s trunk is a hand-drawn monograph published in 1908, Mr Schulz said.
Contrary to popular belief, the trunk doesn’t behave like a straw.
“What they do is drink water in their trunk and keep it,” said Schulz. “So the elephant’s trunk is actually like a trunk.”
Mr. Schulz has completed his research in David Hu’s laboratory, studying how animals move and function in order to apply the discoveries to problems in human engineering. He said one reason the elephant anatomy is poorly understood is because it is difficult to manipulate.
“You are really strong; A lot of people underestimate their strength, ”he said. “And we did experiments in the zoo where they literally destroyed our setups.”
Working closely with zookeepers at Atlanta Zoo, researchers videotaped Kelly, a 34-year-old African female elephant weighing over 7,400 pounds, snapping various types of food. When the elephant was presented with many small cubes of turnip, it breathed in air through its trunk to suck it up. But if the cubes of turnip were larger or few, Kelly preferred to use the two opposite “fingers” of her trunk to grab them instead. The elephant cow also reached for heaps of bran with the fingers of her trunk, presumably so as not to inhale the fine grains.
However, suction feeding was necessary when Kelly faced the most difficult food the researchers put on the table: a single tortilla chip.
Although the tortilla chip was thin, fragile, and difficult to grip on a smooth surface, Kelly was able to use suction to lift and grip the chip without breaking it.
The secret of the elephant’s suction power seems to lie in its large nostrils and specialized respiratory system. Using a non-invasive ultrasound probe, the researchers found that the elephant could widen its nostrils and increase its nasal volume by an impressive 64 percent while sucking up bran-thickened water and storing nearly six liters of fluid in its trunk. After measuring how quickly the elephant could suck up water with its trunk, the researchers calculated that elephant noses could breathe in at speeds of over 150 meters per second, or almost 30 times as fast as humans can sneeze out of ours.
While fish have such sucking abilities, Schulz said the elephant appears to be the only animal on land that “has mastered fluid manipulation both below and above water.”
For example, elephants use their trunks to store emergency supplies of water for drinking and cooling.
“Well, you don’t want to fill this with dust. And you don’t want to fill it with leaves and things, ”said Dr. Garstang. African elephants also eat over 440 pounds of vegetation each day by grabbing leaves one at a time before putting them in their mouths, which would be more efficient than handing over individual leaves.
Still, he said the new study could have useful technological applications to improve robotics. Animal tags like elephant trunks and octopus arms have already inspired innovations in soft robotics, an emerging area that depends on designs of hinge-less flexibility. This research shows how elephants “move both air and water to manipulate various objects,” which is an accomplishment that robots are still difficult to perform, Schulz said.
More detailed studies of elephant biology like this one could also improve conservation efforts for the two species of African elephants that are at risk of disappearing forever from the wild due to habitat loss and poaching. Savannah elephants are now critically endangered, while forest elephants are critically endangered, the numbers of which have declined by more than 86 percent over the past three decades. Many injuries to elephants by poachers and their traps involve the trunk, so a better understanding could help wounded animals recover.
“I hope that people read this and get inspired to work with elephants and get inspired to influence their protection,” said Schulz.