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Mouth-breathing isn't exactly anatomically natural for dolphins. The larynx in the animal ships air to the lungs, while the esophagus brings food to the stomach. The larynx juts through the esophagus and makes respiration and digestion separate systems.
In this case, though, the dolphin seems to have learned to purposely move its larynx such that it's able to breathe directly through its mouth.
It's not yet clear to the researchers why the dolphin has to breathe in this way. Damaged muscles that open and close the blowhole are one possibility, they say, and blockage by a foreign object is another.
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"We are not aware of any published sources describing this behavior in cetaceans," the researchers wrote of the special animal.
Though there are still unanswered questions, one thing seems certain. The mouth-breathing doesn't seem to be harming the dolphin, which looks to have come up with an adaptation to its blowhole issues.
"Whatever the cause of the particular pathology we describe here," the scientists wrote, "repeated sightings of this dolphin over three years and its good current condition indicate that the larynx works well enough for the animal to respire safely."
Findings about the unusual dolphin have been published in the journal Marine Mammal Research.