Winging It
One of the greatest pleasures of my job as a writer is discovering the work of biologists who have ventured into an overlooked corner of nature only to reveal how life there is unfolding in spectacular ways. Meet Sharon Swartz, biology faculty at Brown University. She is the world’s expert on the biomechanics of batwings.
I caught up with Sharon and her colleagues and students one night this past summer. She and her team were working out of a makeshift outdoor laboratory on the grounds of the Southwestern Research Station in the Chiricahua Mountains of southeastern Arizona where they were filming bat flight using a series of high-speed cameras.
Their research demonstrates that bats possess a kind of nimbleness that would make Top Gun gulp with envy. Even seasoned experts like her are stunned by their agility. During our conversation, she recalled one video depicting a bat that had missed its target moth. Turning on a dime, the bat retraced its flight, zeroed in on the insect and then twisted in the air as it folded its wings to successfully scoop up the prey. Although Mexican free-tailed bats have been clocked at impressive speeds of nearly 100 miles per hour, Sharon points out that it’s this control at slow speeds that distinguishes bats’ flight prowess, from snatching prey in mid-air to hovering over a night-blooming flower while draining its nectar.
The list of superlatives doesn’t end there. Not only are bats agile, but they are profoundly resilient. In a flight chamber in her lab at Brown University, Sharon has run experiments in which a wing of a flying bat is hit with a gust of air nearly three times the animal’s body weight. Although the bats are completely knocked off balance, she says, it only takes a single wingbeat cycle for them to get back on track.
This agility and resilience are due, in large part, to the physiology of the animal’s wing, starting with the composition of its skin which is soft and supple, like the skin that covers the inside of your wrist. The skin covering of a batwing also is stretchy like bread dough. These properties give the wing the ability to recoil in a collision.
Batwings, however, are composed of far more than just inert tissues stretched over a scaffolding of bones. Batwings are modified hands. Indeed, they share a remarkable suite of characteristics with the human hand, having nearly the same number of joints and muscles. Bats utilize this complex system of bone and strings of muscle and tendons embedded in the elastic skin for high-level sensing and exquisite flight control that are unlike any other flying animal.
Someday, batwings could inspire the design of more crash-resistant UAVs, Sharon says, or flying assistive devices that help people with physical disabilities safely retrieve items in their home environments. “There are so many things about the natural world that we haven’t observed yet,” she adds. “The challenge for us as organismal biologists is deciding where to look because there’s an infinite number of things that have not been studied.”
For more on Sharon’s research, including spectacular video footage of bats in flight, visit her lab’s website.