Baleen whales proved to own a highly advanced hearing mechanism. Scientists discovered that the bones of the mammals can absorb the sound waves and conducts them towards the ear.
A study published in the PLOS ONE journal, noted that the cranium of baleen whales has evolved to the point that it can feel sounds. Baleen whales, belong to the cetacea group, which includes blue and fin whales, and are filter feeders. It can reach a length of almost 100 feet and can weight up to 400,000 pounds, being the heaviest animal which has ever lived on Earth. For example, the biggest known dinosaur, Argentinosaurus, weighed only half of this weights.
When failing in 2003 to rescue a baby fin whale that got stranded on the beach of Orange County, biologist Ted W. Cranford in collaboration with the engineer Petr Krystl from the University of California, decided to keep the whale’s head for further investigation.
Researchers, shaped the head with a high technology CT scanner. With the help of a process named finite element modelling, they managed to separate the complex construction into small individual pieces. This helped them to observe in a matter of minutes how the skin, bones and muscles would connect and interact with each other.
The computerised image of the whale skull, allowed scientists to mimic how sound would circulate trough the head of the mammal. Whales can hear sounds trough a bony middle ear path, called tympano periodic complex. The heavy waves of a sound are able to travel trough the mammal’s soft tissue, into the tympano periodic complex, with the condition for the waves to be longer than the body of the whale.
This process would be an issue for the blue and fin whales, as both are communicating via low frequency, long wavelength language. Due to an action, named bone conduction, the sounds amplify as they pulsate along the skull. Baleen whales have the ears very firmly tied to their skull, explained scientists.
Earlier studies have assumed that baleen whales are using a certain type of sound bone conduction, but so far none of the studies have brought enough evidence.
Researchers, Cranford and Krysl, discovered that fin whales operate trough bone conduction and this might be their main instrument for hearing.
The method trough which these animals function is overwhelming even for scientists. Until now it has been thought that the loud noises from naval ships or military exercise, was harming the whales, but without any concrete proof it has been difficult for experts to try to legislate the governances.
Even after this discovery, researchers haven’t been able to understand how loud noises from the ocean, can impact the animal’s construction, but for the future they will take these questions into consideration.
Image Source: Discover
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