Tongue-driven sonar beam steering by a lingual-echolocating fruit bat
Wu-Jung Lee1,2, Benjamin Falk2, Chen Chiu2
1Applied Physics Laboratory, University of Washington, Seattle, Washington, United States of America.
Plos Biology
|December 16, 2017
Summary
Egyptian fruit bats steer their echolocation beam using tongue movements, not head or mouth changes. This novel mechanism, akin to engineered phased arrays, allows rapid directional control for efficient sensing.
Area of Science:
- Bioacoustics
- Animal Behavior
- Sensory Ecology
Background:
- Animals use directional sensing for information gathering.
- Echolocating bats control their sonar beam via head or mouth movements.
- Egyptian fruit bats (Rousettus aegyptiacus) use tongue clicks for echolocation, with an unknown beam steering mechanism.
Purpose of the Study:
- Investigate the mechanism of sonar beam control in lingual-echolocating Egyptian fruit bats.
- Explain how these bats achieve rapid changes in echolocation beam direction without visible morphological changes.
Main Methods:
- Recorded echolocation signals from free-flying Egyptian fruit bats.
- Analyzed signal structure, focusing on beam focus and frequency changes.
- Developed computational models to simulate sound emission from tongue-based sources.
Main Results:
- Discovered a unique systematic angular sweep of beam focus across increasing frequencies.
- Observed signal structure inconsistent with the conventional 'piston model' used for other bats.
- Modeled results indicate an array of tongue-driven sound sources steering the beam via phase differences.
Conclusions:
- Egyptian fruit bats employ a novel tongue-based mechanism for echolocation beam steering.
- This mechanism functions similarly to engineered phased array sonar systems.
- Reveals a convergent evolution of beam steering strategies between bats and human technology.
