SATURDAY, Dec. 24 (HealthDay News) -- Reindeer have lots to do
this time of year -- from playing their reindeer games to dragging
heavy sleighs -- but despite all their frenzied activity they
manage to keep cool under luxurious winter coats without getting
dangerously overheated, researchers have found.
Now, Norwegian scientists have gained insight into how they do
it by monitoring the brains of reindeer as they exercised on solid
In the study, the reindeer trotted at speeds of 6 miles per hour
on a treadmill in temperatures from 50 to 86 degrees
"Reindeer are the best animals to work with; once they trust the trainer they will do anything for you," study author Arnoldus Blix, a biologist at the University of Tromso, said in a news release from The Company of Biologists.
Blix and colleagues found that reindeer pant with their mouths
either closed or open, allowing them to evaporate water from either
the nose or the tongue. Evaporating water helps the reindeer to
cool blood in their nasal sinuses; the cooled blood then goes back
to the rest of their bodies.
The researchers also discovered that the reindeer turn to
another strategy when their temperatures get too high: they cool
their brains through a heat-exchange system. They do this by
diverting the blood that had been cooled by going through the nose
to the brain and away from the body. This protects the brain from
The findings were published in a recent issue of the
Journal of Experimental Biology.
Reindeer are unique in other ways. For one, they've lost almost
all signs of the circadian clocks that humans and other animals
have because the day/night cycle at Arctic latitudes is so
Reindeer are also extremely energy-efficient animals, a fact
that allows them to travel great distances -- more than 3,100 miles
a year, at least in American herds.
And, of course, they're able to fly around the world every
Christmas Eve, although they appear to get a big boost from the
powers of imagination.
Learn more about
reindeer from the Smithsonian National Museum of