Bat see with their ears. Which are highly attuned to pick up minute variations in the reflection of the sound pulses they use to echolocate. Here are some pulses, slowed down. [Bat sound.]
And now researchers have shown that horseshoe bats can manipulate the shape of their ears in milliseconds to better catch those bouncing sound waves.
Horseshoe bats had been known to move their entire outer ear, or pinna. But scientists wondered whether the motion was a generalized swiveling of the entire ear—the way a cat can point its whole ear in a specific direction—or whether the bats could delicately manipulate the shape of the pinnae.
The researchers analyzed the pinnae with high-speed video and high-resolution imaging. And they found that the pinnae could move from upright to bent and back again within a tenth of a second, less than the blink of an eye. The study appeared in the journal Physical Review Letters. [Li Gao et al, Ear Deformations Give Bats a Physical Mechanism for Fast Adaptation of Ultrasonic Beam Patterns]
The changes in the deformation of the bats’ ears can correspond to different echolocation beam patterns. Which might allow the bats to tune in to particular frequencies. And you thought wiggling your ears was impressive.
—Cynthia Graber
