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Why Whales Don’t Choke
Scientists have discovered a new anatomical structure that allows lunge-feeding
whales to take in massive amounts of water without choking
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A humpback whale lunge feeding off Vancouver Island in Canada.Credit...Iain
Brownlee/Alamy
By Sam Jones
Jan. 20, 2022Sign up for Science Times Get stories that capture the wonders of
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To capture prey, humpbacks, minkes and other whales use a tactic called lunge
feeding. They accelerate — their mouths open to nearly 90 degrees — and engulf
a volume of water large enough to fill their entire bodies. “It’s crazy.
Imagine putting an entire human inside your mouth,” said Kelsey Gil, a
zoologist studying whale physiology at the University of British Columbia.
As water floods into the whale’s mouth, its throat pouch expands, leaving the
whale looking like a bloated tadpole. After about a minute, the throat pouch
deflates as most of the water leaves the whale’s mouth, released back into the
ocean. Small fish and krill are captured in the whale’s baleen — plates of
keratin that hang from the top of the whale’s mouth resembling bristles on a
toothbrush — and are swallowed into the whale’s stomach.
Scientists didn’t know how these whales avoided choking on prey-filled water
and flooding their respiratory tracts during a lunge feeding event. Now Dr. Gil
and colleagues have discovered a large, bulbous structure that they’ve termed
the “oral plug” — a structure never before described in any other animal — that
they think makes lunge feeding possible. Their results were published Thursday
in Current Biology.
Lunge-feeding whales are also called rorqual whales and include two of the
largest animals on Earth — the blue and fin whales. Through lunge feeding,
rorqual whales ingest thousands of pounds of food every day, a feeding strategy
that allows them to maintain their hulking physiques, which can weigh more than
300,000 pounds in the case of blue whales.
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To determine how these whales are safely chowing down — and not choking — on
their food, Dr. Gil and colleagues analyzed deceased fin whales. When opening
up the mouth of the first whale, they were confused by what they saw.
“If you look in the mirror at the back of your throat, it’s just a big empty
space,” Dr. Gil said. “But when we were looking in the back of this whale’s
mouth, there was this space that was just plugged with tissue, and we thought,
‘That doesn’t make sense. That’s where food has to travel through — why is it
being blocked off like that?’”
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By physically manipulating and dissecting the mass of muscle and tissue — the
oral plug — the researchers determined that when the animal is at rest, the
plug blocks off the whale’s pharynx, a tube-shaped structure that leads to both
the respiratory and digestive tracts, just like in other mammals including
humans. When a whale lunges, the oral plug protects both tracts from being
flooded by the water and the critters that the animal has taken in.
For the whale to ingest food, that oral plug needs to move. Again through
manipulation and dissection, the researchers figured out that when the animal
was ready to swallow its latest meal, the oral plug shifted upward to protect
the upper respiratory tract, including the nasal cavities and blowhole. At the
same time, the larynx — the structure in the pharynx that guards the entrance
to the lungs — closes up and shifts downward, sealing off the lower respiratory
tract. In other words, during swallowing, the pharynx only leads to the
digestive tract and the upper and lower airways are protected.
“This fills in a blank that we didn’t even know really existed,” said Dr. Gil
of the team’s findings.
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Ari Friedlaender, who studies whale feeding behaviors at the University of
California, Santa Cruz but was not involved in this research, sees immense
value in filling in these anatomical blanks about whales.
“The more we can understand how they developed these means for being able to
eat so much, and to be so efficient as foragers, the more we understand about
what their capacities are, and how they function as part of marine ecosystems,”
Dr. Friedlaender said. “It’s sort of the ultimate evolution of anatomy to be
able to do these things that no other animals can do.”
Larry Driscoll
larry.driscoll@xxxxxxxxxxxxx
Why Whales Don’t Choke
Scientists have discovered a new anatomical structure that allows lunge-feeding
whales to take in massive amounts of water without choking.
