Science Current Events | Science News | Brightsurf.com
 

Study Amplifies Understanding of Hearing in Baleen Whales

April 18, 2012

For decades, scientists have known that dolphins and other toothed whales have specialized fats associated with their jaws, which efficiently convey sound waves from the ocean to their ears. But until now, the hearing systems of their toothless grazing cousins, baleen whales, remained a mystery.

Unlike toothed whales, baleen whales do not have enlarged canals in their jaws where specialized fats sit. While toothed whales use echolocation to find prey, baleen whales generally graze on zooplankton, and so some scientists have speculated that baleen whales may not need such a sophisticated auditory system. But a new study by scientists at Woods Hole Oceanographic Institution (WHOI), published April 10, 2012, in The Anatomical Record, has shown that some baleen whales also have fats leading to their ears.

The scientists propose that toothed whales may not be the only whales that use fats to transmit sound in water, as previously believed, and the fats in both types of whales may share a common evolutionary origin.

Little progress had been made on the auditory anatomy of baleen whales because specimens to study are hard to get. Unlike many toothed whales, they are large, not kept in captivity, rarely strand on beaches, and decompose rapidly when they do.

For the new study, lead author Maya Yamato, a graduate student in the MIT/WHOI Joint Program in Oceanography, received seven heads of minke whales that stranded and died, mostly on beaches on Cape Cod. She collaborated with the International Fund for Animal Welfare's (IFAW) Marine Mammal Rescue and Research unit in Yarmouth Port, Mass.

The whale heads were scanned using computerized tomography (CT) and magnetic resonance imaging (MRI) at the Computerized Scanning and Imaging (CSI) lab at WHOI and MRI facility at Massachusetts Ear and Eye Infirmary in Boston. Using these biomedical techniques, the researchers generated 3-D visualizations of the whales' internal anatomy, with both bones and soft tissue intact and in their undisturbed natural positions, providing "an unprecedented view of the internal anatomy of these animals," the scientists wrote.

Then the whale heads were dissected in the necropsy facility at the Marine Mammal Center at WHOI. Together, the studies showed that all the minke whales had "a large, well-formed fat body" connecting to the ears, providing a potential transmission pathway guiding sound from the environment to their inner ears.

"This is the first successful study of intact baleen whale head anatomy with these advanced imaging techniques," said WHOI Senior Scientist Darlene Ketten, director of the CSI lab at WHOI and co-author on the paper. "It really is an important addition to our understanding of large whale head and auditory systems."

Also collaborating on the study were Julie Arruda and Scott Cramer at the CSI and Kathleen Moore of IFAW.

This research was funded by a National Science Foundation Graduate Research Fellowship, a WHOI Ocean Life Institute Graduate Fellowship, the Joint Industry Program, the Office of Naval Research, and the U.S. Navy.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans' role in the changing global environment. For more information, please visit www.whoi.edu

The Woods Hole Oceanographic Institution


Related Baleen Whales Current Events and Baleen Whales News Articles


Ship noise extends to frequencies used by endangered killer whales
When an endangered orca is in hot pursuit of an endangered salmon, sending out clicks and listening for their echoes in the murky ocean near Seattle, does the noise from the nearby shipping lane interfere with them catching dinner?

Microplastics: Rhine one of the most polluted rivers worldwide
Between Basel and Rotterdam, the Rhine has one of the highest microplastics pollution so far measured in rivers, with the Rhine-Ruhr metropolitan area showing peak numbers of up to four times the average.

Unique feeding mechanism among marine reptiles from the age of dinosaurs
Fossils of the elasmosaur Aristonectes were first reported from the Late Cretaceous of Patagonia in 1941.

Researchers identify 3 new fossil whale species of New Zealand
University of Otago palaeontology researchers are continuing to rewrite the history of New Zealand's ancient whales by describing two further genera and three species of fossil baleen whales.

Listening for whales and fish in the Northwest Atlantic ocean
Scientists are using a variety of buoys and autonomous underwater vehicles to record and archive sounds from marine mammals and fish species in the western North Atlantic through a new listening network known as the U.S. Northeast Passive Acoustic Sensing Network (NEPAN).

Research details 40 million-year-old family tree of baleen whales
New research from New Zealand's University of Otago is providing the most comprehensive picture of the evolutionary history of baleen whales, which are not only the largest animals ever to live on earth, but also among the most unusual.

Scientists reconstruct evolutionary history of whale hearing with rare museum collection
A team of scientists from the Smithsonian's National Museum of Natural History gained new understanding about the evolutionary history of whale hearing thanks to a rare collection of whales at the museum.

Scientists reconstruct evolutionary history of whale hearing
Changes in ear bone development in the womb paralleled changes observed throughout whale evolution, providing new insight about how whales adapted to hearing underwater.

Passive Acoustic Monitoring Reveals Clues to Minke Whale Calling Behavior and Movements in the Gulf of Maine
Scientists using passive acoustic monitoring to track minke whales in the Northwest Atlantic have found clues in the individual calling behaviors and movements of this species.

Plankton make scents for seabirds and a cooler planet
The top predators of the Southern Ocean, far-ranging seabirds, are tied both to the health of the ocean ecosystem and to global climate regulation through a mutual relationship with phytoplankton, according to newly published work from the University of California, Davis.
More Baleen Whales Current Events and Baleen Whales News Articles

© 2016 BrightSurf.com