Seals have a trick to more effectively retain heat and moisture when breathing in and out. They do this thanks to special nasal passages. Their elaborate structure means that Arctic seals lose less heat through nasal heat exchange than subtropical seals. This is what study author Signe Kjelstrup, from the Norwegian University of Science and Technology, says.
This is an evolutionary advantage, especially in the Arctic. There heat loss is dissipation of energy, which must be replaced with food. The surprising thing is that these arctic seals retain 94% of the water when they breathe in and out. Most of the water added to the air during inhalation is then recovered during exhalation.
Respiratory efficiency
In cold, dry environments, animals lose heat and moisture just by breathing. Most mammals and birds have complex bones called maxilloturbinates inside their nostrils. They help minimize this risk. They warm and humidify inhaled air, which is important for lung function. And they reduce the amount of heat and moisture lost during exhalation.
This study was published in the ‘Biophysical Journal’. They used energy dissipation models to compare the seals’ ability to heat and humidify the air. Arctic seals were shown to be much more efficient than subtropical seals at retaining heat. This advantage was due to the more complex and dense nasal cavity of the Arctic seal. The maxilloturbinates of the Arctic seal are larger. This is key to limiting power dissipation at low ambient temperatures.
Air-conditioning
Knowing how seals endure the Arctic cold may have practical applications. The researchers plan to use this information to design more efficient heat exchangers and ventilation systems. «Nature manages to create very good heat exchangers. I think we should copy them in engineering to create more efficient processes. For example, in air conditioners,” suggests Kjelstrup.
