Tiny Muscles in Bat Wings Fine-Tune Amazing Flights

Bats are excellent flyers, soaring through the night skies as they quickly maneuver to catch insects or feed on fruit. Now, scientists have found that bats have a capability within their wings that may explain how they fine-tune their flight.

Researchers have known for years that bats possess tiny muscles, called plagiopatagiales, in their wings. Yet until now, scientists have been unsure exactly what their function is. In this case, the scientists believed that the muscles could potentially be used to change the bat's wing shape, and thus improve aerodynamic performance.

"Aerodynamic performance depends upon wing shape," said Jorn Cheney, one of the researchers, in a news release. "The shape of a membrane wing might initially begin flat but as soon as it starts producing lift, it's not going to remain flat because it has to deform in response to that aerodynamic load."

Yet the only way to find out whether they were correct or not was through experimentation. The researchers attached electrode sensors to a few muscles on the wings of Jamaican fruit bats and then filmed them as they flew in their lab's wind tunnel.

So what did they find? It turns out that plagiopatagiales modulate skin stiffness. Muscle activation and relaxation actually allows the bats to follow a distinct pattern during flight; they tense on the downstroke and relax on the upstroke. In addition, the muscles work together rather than individually and activated with different timing at different flight speeds.

"The shape it adopts could be a terrible one-it could make the animal crash-or it could be beneficial," said Cheney in a news release. "But they are not locked in that shape. Because bats have these muscles in their wings, and also bones that can control the general shape as well, they can adopt any number of profiles."

The findings reveal a little bit more about bat flight. This, in turn, could allow researchers to use what they observed in order to create flying robots. Currently, researchers are actually improving a robotic wing by integrating the new findings from this particular study.

The findings are published in the journal Bioinspiration and Biomimetics.