A ‘trapdoor’ made of muscle and fat helps fin whales eat without choking
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Some of the world’s largest whales feed by lunging through the water with mouths wide open. Scientists have long wondered how the animals withstand the tremendous pressure of water rushing into their throats without choking and drowning.
A plug made of muscle and fat found at the back of fin whales’ mouths might offer a clue. The plug blocks the channel between a fin whale’s mouth and its pharynx, the entrance to the respiratory and digestive tracts. The plug appears to prevent water from rushing into the whale’s lungs and stomach while it lunges and could explain how all lunge-feeding whale eat without choking, researchers report January 20 in Current Biology.
“Think of [the plug] as a trapdoor,” says Kelsey Gil, a marine biologist at the University of British Columbia in Vancouver. “It’s always closed unless muscular activity pulls it out of the way.”
Gil and her team identified the plug after examining the pharynx of 19 fin whales (Balaenoptera physalus) recovered from an Icelandic whaling station. Because fin whales are prodigious eaters and can weigh up to 100 metric tons, the size of a midsized passenger plane, it was easier to work with just the pharynx (SN: 11/3/21).
“Even then we had to use a forklift to move the pharynx to the lab. It can weigh a few hundred pounds,” says Gil.
Once the samples were in the lab, she and her team manipulated different structures in the pharynx to see how they could move and looked at which direction muscle fibers ran within the whales’ throat to understand how the muscles behave when they contract.