The Evolutionary History of Whale Hearing Parallels Fetal Development

Scientists have learned a bit more about the evolutionary history of whales. After using CT scanning on fetal whale specimens, researchers have confirmed that changes in the development of ear bones in the womb parallel changes observed throughout whale evolution.

"Whale ears are incredibly complex organs," said Maya Yamato, lead author of the new study, in a news release. "Although scientists know that hearing is one of the most important senses that whales use to communicate, navigate and search for food in their underwater world, we are still searching for clues about how their ears actually work."

Whales rely on sound to communicate with each other. Some species, like humpbacks, are known for their underwater songs. Toothed whales also rely on sounds to navigate and forage by emitting calls and echolocation. Understanding how whales hear is crucial to protecting future populations of these creatures.

In order to learn a bit more about whale hearing, the researchers used innovative imaging methods to identify and depict the development of a specific area of the ear found exclusively in whales, called the "acoustic funnel." The scientists used X-ray computed tomography (CT) to scan images of fetal whales found in museums. These specimens represented 15 different species of modern whales ranging in size from blue whales to harbor porpoises.

The CT scans revealed that the early developmental stages of whale ears are extremely fragile. As the ears continue to mature, the basic mammalian structures rearrange to form the "acoustic funnel," which may play a crucial role in underwater hearing. What's interesting is that the changes mimic what occurred in evolution; whales were once land-based and their hearing evolved when they took to the sea.

The findings are published in the journal PLOS One.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).