Heavy drinkers are baleen whales. In just ten seconds, these giant mammals can down over five hundred bathtubs of ocean water, and remove roughly 10 kilograms of krill from a single swig.
All they have to do is open their mouths and lunge forward.
The pressure of the water hitting the whale's throat would be immense. The group of creatures that include right whales, the humpback whale, and the monumental blue whale make sure their lungs aren't suddenly flooded with water.
The fin whales have a muscular sac that stops them from choking. This sac plugs the lower respiratory tract when the whale opens its mouth to feed.
The authors think it's possible that the structure is present in other whales, like blue whales.
The oral plug is likely a protective structure that is necessary to enable lunge feeding because there are very few animals with lungs that feed by engulfing prey and water.
Gil and her colleagues think the oral plug works like a railroad switch, since it pops out when a whale breathes. The plug completely blocks off this pathway when a whale feeds.
The epiglottis is a flap of tissue that covers the path to the lungs when we are eating.
When whales are breathing through their blowholes, they use a plug in their soft palate to keep water out of their lungs.
The whale's upper blowhole has to be shut off when they are eating so that they can swallow.
The force of incoming water pushes the whale's tongue back against the epiglottis, closing the lower airway as well.
Swallowing and breathing in fin whales. Alex Boersma is a current biology researcher.
Gil says that it's similar to when a human's windpipe closes up while swallowing food.
The throat structures in whales are very different from those in humans.
"Bulk filter-feeding on krill swarms is the only way to provide the massive amount of energy needed to support such large body size," says zoologist Robert Shadwick from the University of British Columbia.
The special features we have described would not be possible without them.
It takes a lot of energy for a fin whale to swim.
There's still a lot to learn about these giant creatures. How do whales blow bubbles? Do they burp or hiccup?
To see a baleen whale eat and breathe in real time, the authors would need to create a swallow-able camera.
In the meantime, the dissections were not done on whales caught for scientific purposes, but performed on whales that have not been killed in the last few years.
The study was published in Current Biology.
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