MELBOURNE, July 16 (Xinhua) -- New research shows how a specialized ear tissue enables seals to hear both underwater and on land, offering insight into the adaptation of marine mammals in increasingly noisy oceans.
The study, led by Australian and British researchers, finds the earliest marine seals evolved "amphibious hearing" -- the ability to hear effectively in both air and water -- more than 26 million years ago, a trait fundamental to their survival, according to a statement released by Australia's Monash University on Wednesday.
The findings are highly relevant as human-driven ocean noise intensifies due to commercial shipping, sonar, and offshore construction, researchers said, adding that without understanding the natural baseline of seals' unique hearing, it is difficult to assess the damage caused by noise pollution to marine species.
The study, published in Proceedings of the Royal Society B: Biological Sciences, identifies a specialized ear tissue that enables "amphibious hearing," a "superpower" among mammals.
"Most mammals are unable to hear properly underwater, but seals evolved ears specialized for hearing underwater without compromising their ability to hear on land," said James Rule from the Monash School of Biological Sciences, the study's lead author.
By analyzing CT scans and data from both modern and fossil museum specimens, and drawing on recent advances in pinniped evolution, researchers were able to understand the origins of their amphibious hearing and thus their complex underwater communication.
"This evolutionary innovation facilitated the remarkable vocal diversity of pinnipeds, which allows them to communicate both on land and in the ocean," Rule said. ■
