Lunge-feeding baleen whales have an 'oral plug' in their mouths that helps them to gulp down food underwater without drowning in the process, a study has found.
As the marine mammals thrust though the ocean taking in vast volumes of krill bearing water, this fleshy bulb seals off the airways to stop water entering the lungs.
When they swallow, it shifts to block off the upper airways (nasal cavity) while the entrance to the larynx is closed and the laryngeal sac blocks off the lower airways.
This leaves a path between from mouth to stomach through which krill — filtered out of the water by their bristle-like 'baleen' plates — can then be ingested.
No anatomical feature like an oral plug has even been seen before in any other animal, reported the research team from the University of British Columbia.
Lunge-feeding baleen whales (or fin whales, pictured )have an 'oral plug' in their mouths that helps them to gulp down food underwater without drowning in the process, a study has found
The study was conducted by marine biologist Kelsey Gil and her colleagues at the of University of British Columbia.
'We discovered a structure in fin whales, which likely exists in all lunge-feeding whales, or rorquals,' explained Dr Gil.
'We've termed it the "oral plug" and found that it blocks the channel between mouth and pharynx,' she added.
'It means that when a whale lunges, the entrance to the pharynx and thus the respiratory tract is protected.
'It's kind of like when a human's uvula moves backwards to block our nasal passages and our windpipe closes up while swallowing food.'
Studying whale anatomy is difficult, because it often involves trying to perform dissections on specimens that have died after stranding themselves on the coast in the limited period of time before the tide rises to cover the carcass.
In the present study, however, Dr Gil and her colleagues were able to study the unwanted parts of whales collected at a commercial whaling station in Iceland.
Part of the study involved physically manipulating the various anatomical structure in order to see how they were able to move.
The team also looked at the
