The long-eared bat, which is native to Europe, has gigantic ears that seem to be important for echolocating and finding prey. These big floppy ears don't look ideal for flying, but it turns out that they might actually help bats stay in the sky. In a new study in Scientific Reports, a team of researchers describe how a bat's big ears keep it aloft—and could provide inspiration for next-generation drones.
Bats, which make up one-fifth of all mammalian species, are bizarre creatures. They owe their evolutionary success to flight and echolocation, although in a sense, the two were thought to be at odds. "Together, flight and echolocation have enabled bats to forage in the night sky, a niche that presumably was relatively unexploited until bats emerged about 65 [million years] ago," researchers from Lund University, in Sweden, write in their paper. "At the same time, the ability to fly and echolocate efficiently is not without conflict."
In other words, their big ears could slow them down, or knock them off course.
In the study, a team led by biologist Christoffer Johansson Westheim put three trained bats inside a wind tunnel, and got them to fly through smoky air towards a mealworm snack. Then they zapped a laser beam at the smoke behind the bats to illuminate its particles. That gave them a view of the "wake" that bats created in the smoke—how they stirred up the air as they moved—and an idea of the force generated by each pump of their wings.
Turns out that big ears actually help these bats fly.
"We show how the air behind the body of a long-eared bat accelerates downwards, which means that the body and ears provide lift," Johansson Westheim said in a release that accompanied the study. The team also found that, when flying slowly, bats generate forward movement by holding their wings high, away from the body, at the end of each beat.
"This specific way of generating power could lead to new aerodynamic control mechanisms for drones in the future, inspired by flying animals," Johansson Westheim continued.
If these findings do go on to inform the design of drones, it wouldn't be the first time. As previously reported on Motherboard, scientists are already borrowing ideas for drone wings from bats and birds. At the University of Southampton in the UK, another group recently announced they'd designed wings for drones that were inspired by batwings, and can actually change shape in response to various forces, like "artificial muscles." Bats, this team noted, are the only mammals capable of flight.
Engineers will keep looking to nature for inspiration. Unlike manmade flying machines, the bat's body plan has been under development for millions of years.