Deaf, snakes? Not exactly. They are sensitive to ground vibrations, and a new study shows that the python can also feel the vibrations caused by sound waves in air. Everything happens in the head.
Snakes have no external ear. To say they do not hear, there is a margin … We already knew they were able to feel the vibrations of the ground with a hearing aid simplified. To avoid snakes circulating among the tall grass, it is also advisable to throw stones in front of you As we walk. Stones falling to the ground cause because vibrations that are felt by snakes, and frightening.
For if the serpent does not own or outer ear (like the flag of humans) or eardrum, it is however equipped with a rudimentary auditory system, consisting essentially of an inner ear, connected to the mandible by a small bone, columella. The jaw, which is in contact with the ground when the snake moves there, collects and transmits vibrations to the inner ear.
In the head of the royal python, ground vibrations are felt in the mandible and the quadrate bone. The vibrations are transmitted to the inner ear through the columella.
In the head of the royal python, ground vibrations are felt in the mandible and the quadrate bone. The vibrations are transmitted to the inner ear through the columella. © Christensen et al. 2011, Journal of Experimental Biology – adaptation Futura-Sciences
The royal pythons: snakes to listen
But what about sounds that are not from the ground but the air? Snakes are really deaf? Biologists from the University of Southern Denmark wanted to see by imagining an experience of Physiology. Published in the Journal of Experimental Biology, Tinnitus Miracle the results show that snakes also receive a sound emitted into the air through a system similar to that which is used to detect ground vibrations.
The researchers suspended a loudspeaker on top of royal pythons (Python regius), after fixing the electrode in contact with the neurons in order to detect potential activity. They therefore tested a variety of sounds, ranging from 80 to 1000 Hz and 50 to 110 dB (sound pressure for a 20 ìPa).
With frequencies between 80 Hz and 110 royal pythons that react the most. This sensitivity to bass is surprising, the researchers said, because the sound range is rare in the natural environment of the animal.
The skull receives the vibrations of the air
The second was to ensure that the snakes were very sensitive to the propagating wave in the air and not to those transmitted to the ground. The scientists then repeated shaking on the floor of the same intensity as those that occurred during the emission of a sound. Too low, they were not detected by pythons, proof that it is the wave propagating in the air makes them tick.
But how do they feel? Thanks to the vibrations that cause sound waves within the skull of the animal. The snake is not sensitive to sound waves as can be a vertebrate with a tympanum. He sees through the vibrations of the skull, in the same way he feels the vibrations from the ground.
What other vertebrates that have only rudimentary auditory system? Difficult to generalize the case of the ball python and it will probably study for each species in order to find out.