A monitor lizard ignores the textbook explanations of how it should breathe and instead it whooshes air through its lungs in a one-way flow, just as birds do.
As mammals breathe, air flows like a tide into the lungs and then back out through the same tubes. Birds also move air in and out of their mouths and noses. But inside their lungs, birds route air in one direction only. Lizards, in theory, had tidal lungs like mammals. Rethinking that upsets ideas about lung evolution.
Sensors implanted in the lungs of live savannah monitor lizards (Varanus exanthematicus) showed air blowing one way, says Colleen G. Farmer of the University of Utah in Salt Lake City. Breath moves through the animal’s multichambered lungs from the tail end toward the head. Farmer’s group found air wafting from one chamber to another through walls dotted with openings “like lace curtains,” she says.
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