ScienceShot: Cool Reindeer Heads Prevail at the North Pole
Staff Writer  Prancing around in fluffy fur coats, reindeer stay
plenty warm when temperatures plummet below -50°C, but they
can't exactly unzip to cool off after exercise. To study how
reindeer avoid overheating, researchers rounded up nine of the
friendliest animals they could find and implanted probes into
major blood vessels in their heads that measured blood flow and
brain temperature. Then they let the reindeer run on a specially
designed treadmill. At first the reindeer breathed through their
noses, allowing the Arctic air to cool the blood in their
sinuses before sending it on to the rest of the body. But once
they started breathing faster, up to 260 breaths per minute,
they opened their mouths and panted like dogs, letting the air
flow over their big tongues to cool that blood. When their brain
temperature reached a critical limit of 39°C, researchers report
today in December issue of The Journal of Experimental Biology,
the reindeer switche