Some textbooks still say snakes are deaf. Scientists have already suspected that this cannot be true. A new study now supports the assumption - and shows that snakes can very well perceive sound through the air.
Even without visible ears, snakes are anything but deaf. A study in the journal "PLOS One" shows that the animals not only perceive the smallest vibrations over the ground, but also sound over the air.
Snakes have an inner ear but no eardrum, says the biologist and reviewer of the study, Ulrich Joger. Some textbooks still say that snakes are deaf. According to Joger, former director of the State Natural History Museum in Braunschweig, scientists have already suspected that this is wrong. It was previously known that snakes sense ground vibrations by laying their heads on the ground. Vibrations cause both halves of the lower jaw to vibrate, the scientist explains. These vibrations would then be transmitted through a series of bones to the inner ear.
Australian researchers have now investigated whether snakes also react to sound in the air. Part of the experiment were 19 captive-born animals of six different species that are mainly found in Australia: from the woma python, which can be up to three meters long, to the taipan, one of the most venomous snakes in the world, to the brown snake, also very venomous .
Three different sound frequencies were played to the reptiles in a soundproof room, explains the researchers led by Christina Zdenek from the University of Queensland in Brisbane, Australia. They observed how the snakes reacted, paying attention to body, head, jaw, tongue and hissing sounds. One of the frequencies produced ground vibrations, the other two sound waves in the air.
The reaction of the snakes was strongly dependent on their species. While the boa snake Woma moved toward the sound, the smaller poison snakes tended to move away from it, the study says. The nocturnal woma python has few natural enemies. Therefore, she does not have to be as cautious as smaller species and tends to move in the direction of the sound. Taipans, on the other hand, have to protect themselves from birds of prey, for example, and are therefore probably more sensitive to noise. But Joger said too few snake species were part of the experiment to really support such an interpretation. Further investigations are needed.
