Dolphins can use their teeth to hear underwater, as an interface between sound vibrations in the water and the auditory system. Teeth may be “like the tactile hairs that some animals use”, says new study.
Dolphins’ teeth may serve them as sophisticated tools for detecting sounds underwater, with a particularly relevant role in echolocation, according to a Nov. 12 study in Wiley.
The study, carried out by Ryo Kodera and his team at the University of Tsurumi in Japan, found that dolphins’ teeth are connected to thick bundles of nerve fibers, which can function as a interface between sound vibrations in the water and the auditory system.
“Our results support the hypothesis that dolphins use their teeth as part of an advanced sound reception system”, explains the author, cited by the magazine.
Dolphins and other toothed whales, known collectively as odontocetes, are known to have many teeth, many of which are not used for chewing. Researchers believe these teeth may even play a role in reception of sound waves.
O cochlear nervecrucial for auditory processing, binds to fat in the lower jaw, indicating a potential link between sound vibrations, teeth and the brain.
Kodera’s team examined jaws from several odontocete species, including the bottlenose dolphin and false killer whale, and compared them to those of land mammals such as domestic pigs.
The researchers noticed unique features in the jaws of odontocetes, such as a looser placement of the teeth, more spongy and porous alveoli, and thick nerve bundles that connect the teeth.
These nerves are surrounded by fatty insulation, allowing rapid transmission of electrochemical signals, and are thicker than those of land mammals.
“These findings suggest greater sensitivity to tooth movement, possibly comparable to the tactile hairs that some animals use to touch“, says Kodera. However, the study does not conclusively prove that these nerve bundles directly help echolocation or hearing.
Experts in the field praised the study, but did not fail to point out its limitations. Philippe Blondel, from the University of Bath, stresses that more research is needed to determine the specific sensory functions of the fibers.
Robert Boessenecker, from the University of California Museum of Paleontology, considers the findings to be at least groundbreaking and believes the study “will influence the way we examine dolphin jaws in the future.”
