Despite the widespread myth that snakes (lacking outer ears, a tympanic membrane and other evidence organs of audition) cannot hear, it seems we have been too dismissive about these reptiles’ sensory abilities.
According to physicists Paul Friedel and J. Leo van Hemmen of the Technical University in Munich and Bruce Young of Washburn University in Kansas, however, not only can snakes hear. They can hear in stereo. Through their jaws.
Snakes’ jaws are connected to an inner ear with functional cochlea. Resting on the ground, a snake’s jaw can detect tiny vibrations that act like sound waves, the physicists will report in an upcoming issue of Physical Review Letters. As a result, the footsteps of, say, a mouse—to say nothing of the footsteps of a person—cause surface waves to propagate in the ground, which the snake detects as sound and “should be regarded as significant sensory input,” conclude the scientists.
They carried out a geometric study of the anatomy of desert horned vipers and the ground waves created by the footsteps of their prey. The jaw-to-cochlea system, it turns out, is attuned to the frequencies of the prey’s ground vibrations. Worse (for anyone or anything planning to tiptoe past a snake), snakes’ ability to unhinge their jaws and swallow their prey whole means the right and left jaws can receive vibrations independently. In other words, snakes hear in stereo, and so can use the auditory information to pinpoint the locations of passers-by.