Adjusting to life in cold air temperatures has been key to survival for the Arctic’s seals. Those adaptations go beyond thick layers of blubber for insulation and up into the pinniped’s nose. A study published December 14 in the Biophysical Journal found that Arctic seals have more convoluted nasal passages than seals that live in more mild places.
[Related: Hungry seals may have begun following their whiskers 23 million years ago.]
Warming the air
In cold and dry places, animals lose moisture and heat when they breathe. Warmer and wet air is important for lung function, so breathing in cold air can put the lungs in danger and may make humans more susceptible to respiratory viruses. To help minimize the risk, most birds and mammal species have complex bones called maxilloturbinates inside their nasal cavities. These porous, bony shelves are covered with mucus and tissues that warm and humidify inhaled air. Maxilloturbinates also reduce the amount of heat and moisture that is lost when an organism breathes out.
Researchers believe that the nose structure helps Arctic seals efficiently retain moisture and heat as they inhale and exhale.
“Thanks to this elaborate structure in their nasal cavities, Arctic seals lose less heat through nasal heat exchange than subtropical seals when both are exposed to the same conditions,” Signe Kjelstrup, a study co-author and physical chemist at the Norwegian University of Science and Technology, said in a statement. “This provides an evolutionary advantage, especially in the Arctic where heat loss is energy dissipation, which must be replenished by food.”
According to Kjelstrup, Arctic seals retain 94 percent of the moisture in the air when they breathe in and out. Most of the water added to the air when they inhale is then recovered when they exhale.
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The structure of maxilloturbinates varies between species.
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