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To catch their prey, humpbacks, minkees and other whales use a tactic called thrust feeding. They speed up – their mouths open to about 90 degrees – and swallow a large volume of water large enough to fill their entire body. “This is insane. Imagine putting a whole person in your mouth,” he said. Kelsey Gil, a zoologist studying whale physiology at the University of British Columbia.
As the water flows into the whale’s mouth, the throat sac expands, making the whale look like a whale. swollen tadpole. After about a minute, the throat sac deflates as most of the water leaves the whale’s mouth and is released back into the ocean. Small fish and krill are caught in the whale’s whale — the keratin plates that hang from the top of the whale’s mouth and look like bristles on a toothbrush — and are swallowed into the whale’s stomach.
Scientists did not know how these whales avoided drowning with prey-filled water and overflowing into their airways during a thrust feeding event. Now, Dr. Gil and colleagues have discovered a large, bulbous structure they call the “mouth plug”—a structure never previously described in any other animal—that makes it possible to feed by spurt. The results were published on Thursday. Current Biology.
Lung-feeding whales are also called rorqual whales and include: the two largest animals in the world — blue and fin whales. Rorqual whales swallow thousands of pounds of food each day through lunge feeding; 300,000 poundsin the case of blue whales.
Dr. Gil and colleagues analyzed dead fin whales to determine how these whales did not safely suffocate and choke on food. When they opened the mouth of the first whale, they were stunned by what they saw.
Dr. “If you look in the mirror at the back of your throat, it’s just a big gap,” Gil said. “But when we looked at the back of this whale’s mouth, there was a space clogged with tissue and we thought, ‘This doesn’t make sense.’ That’s where the food has to go – why is it blocked like that?”
By physically manipulating and breaking down the muscle and tissue mass (mouth plug), the researchers determined that when the animal was at rest, the plug blocked the whale’s pharynx, a tube-shaped structure that leads to both the respiratory and digestive tracts. just like other mammals, including humans. When a whale makes a move, the mouth plug protects both paths from being overrun by the water and the creatures the animal has engulfed.
In order for the whale to swallow the food, this mouth plug must move. Again through manipulation and dissection, the researchers found that when the animal is ready to swallow its last meal, the mouth plug slides upward to protect the upper airway, including the nasal cavities and air hole. At the same time, the larynx, the structure in the pharynx that protects the entrance to the lungs, closes and slides down, closing the lower airways. That is, during swallowing, the pharynx only leads to the digestive tract, and the upper and lower airways are protected.
Dr. “This fills a void we didn’t even know existed,” Gil said of the team’s findings.
Ari FriedlaenderD., who studies whale feeding behavior at the University of California, Santa Cruz, but was not involved in this research.
“The more we understand how they evolved these tools to be able to eat that much and be as efficient as foragers, the better we understand what their capacity is and how they function as part of marine ecosystems,” he said. said Friedlaender. “Being able to do these things that no other animal can do is like the ultimate evolution of anatomy.”
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