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Why whales don’t drown when they eat underwater

After taking a deep dive inside a whale's mouth, researchers at UBC have uncovered why these animals don't choke or drown when they eat

Scientists at the University of British Columbia are taking a deeper dive into how whales can eat underwater and have uncovered the secret. 

Dr. Kelsey Gil, a postdoctoral researcher in the department of zoology, has been studying the inside of whale mouths since 2018 to find out how they can eat underwater after consuming gallons of water and prey. 

Using a whale from Iceland, Gil and her team were able to recover tissue from a whaling station and determined just how they eat. 

"When they open up their mouths to engulf a volume of food and water, that can be as large as their own body, that oral plug is right at the back of the mouth and it is preventing any of that water from going down into the respiratory tract or prematurely entering the digestive tract,” Gil tells Glacier Media.

Once the whales have pushed all of the water out of their mouth, that big plug at the back of their mouth has to be moved out of the way. 

"There are muscles that contract and it pulls the plug backwards and upwards so it blocks off the entryway to their nasal cavities,” she says.

Similar to humans when our nasal passages are blocked and we swallow food. 

"I am impressed with how similar this mechanism is to humans swallowing so that is a fun feature too,” Gil says.

Given the size of the whales, the UBC researcher says getting the information can be pretty challenging. 

"We try our best to work on animals that have died along the coastline here so participating in necropsies and trying to get tissue. But these whales are very large and it’s very hard to access that part of that throat,” Gil says.

She adds they haven’t seen this protective mechanism in any other animals, or in literature. 

"A lot of our knowledge about whales and dolphins comes from toothed whales, which have completely separated respiratory tracts, so similar assumptions have been made about lunge-feeding whales,” she says. (Like the name suggests, lunge feeding involves a whale lunging through the water with their mouth wide open.)

The research allows a closer look into lunge-feeding, which is believed to be why these animals are the largest on the planet.

"It’s a really important part of lunge-feeding because it is protecting all of the pharynx and respiratory and digestive tract there, so it's giving us more answers to how lunge-feeding might have developed or adaptations that are required for lunge-feeding,” she says.

Dr. Robert Shadwick, a professor in the UBC department of zoology, says a whale’s oral plug and closing larynx is central to how lunge-feeding evolved. 

“Bulk filter-feeding on krill swarms is highly efficient and the only way to provide the massive amount of energy needed to support such a large body size. This would not be possible without the special anatomical features we have described,” says Shadwick. 

The team is also trying to determine if whales cough, hiccup or burp. 

“Humpback whales blow bubbles out of their mouth, but we aren’t exactly sure where the air is from — it might make more sense, and be safer, for whales to burp out of their blowholes,” Gil says. 

She calls the discovery "fantastic."

"I am really happy that we are able to do this research and answer questions that haven’t really been answered yet.”