John Zook's studies of bat flight suggest that touch-sensitive receptors on bats' wings help them maintain altitude and catch insects in midair. His preliminary findings, presented at the recent Society for Neuroscience meeting, revive part of a long-forgotten theory that bats use their sense of touch for nighttime navigation and hunting.
The theory that bats fly by feel was first proposed in the 1780s by French biologist Georges Cuvier, but faded in the 1930s when researchers discovered echolocation, a kind of biological sonar found in bats, dolphins and a few other animals. Bats use echolocation to identify and navigate their environment by emitting calls and listening to the echoes that return from various objects.
Zook believes the touch-sensitive receptors on bats' wings work in conjunction with echolocation to make bats better, more accurate nocturnal hunters. Echolocation helps bats detect their surroundings, while the touch-sensitive receptors help them maintain their flight path and snag their prey.
Touch receptors take the form of tiny bumps, or raised domes, along the surface of bats' wings. The domes contain Merkel cells, a type of "touch" cell common in bumps on the skin of most mammals, including humans. Bat touch domes are different, however, because they feature a tiny hair poking out of the center.
When Zook recorded the electrical activity of the Merkel cells, he found they were sensitive to air flowing across the wing. These cells were most active when airflow ?particularly turbulent airflow ?stimulates the hair. When a bat's wing isn't properly angled or curved during flight, air passing next to the wing can become turbulent. Merkel cells help bats stay aerodynamical