Bats Fine-Tune Flight Using Touch Receptors

Bats are well known for their ability to fly in the dark with great precision. They can navigate the night sky with ease while avoiding obstacles such as predators and trees. They can even find a midnight, midair meal—plucking flying insects right out of the darkness.

It is generally accepted that bats are able to navigate and hunt at night thanks to a sensory ability known as echolocation. Echolocation is a kind of 'biological sonar' that enables the bats to construct an image of their surroundings by first emitting high-pitched screeches and then detecting the echoes that come back to them as the sound bounces off surfaces in their surroundings. In recent decades, bat research has focused on the animals' ability to use ecolocation to navigate and maneuver in flight.

But as it turns out, there is more to bat aerobatics than merely echolocation and bats have a more complex sensory repetoire than previously thought. A recent study by Ohio University Professor John Zook has revealed that bats have touch-sensitive receptors on their wings and that those receptors enable them to fine-tune flight and capture prey. The touch sensors are actually tiny bumps on bats' wings that are particularly sensitive to the airflow over the wing thanks to a small hair that grows out of each bump and senses air turbulance.

John Zook believed that the touch receptors that cover the bat's wings work together with echolocation to provide precise biofeedback about flight posture and enable the bat to capture prey with great accuracy. He put his ideas to the test by removing some of the tiny hairs from the bats wing using hair removal cream. He then observed how the bat flew with 'bald' wings. The bats were able to fly in a straight line without problems but they had great difficulty making turns. Professor Zook described their erratic flight behavior:

"It was obvious they had trouble maintaining elevation on a turn. Without the hairs, the bats were increasing the curve of their wings too much or not enough."

Zook then allowed the hairs on the bat's wings to re-grow. When the hairs were once again covering the bat's wings, they bat was able to fly normally.

Zook also found that bats have another type of receptor cell built into their wings that records the stretch of the wing membrane. He named these areas 'sweet spots' and discovered that it is in these parts of the wing that the bat prefers to capture its prey.

Find out more: Bats Use Touch Receptors on Wings to Fly, Catch Prey, Study Finds (Ohio University)

Photo © John Zook / Ohio University. Close up images show the raised domes that contain touch receptors.