Without oxygen, a mere human dies in minutes, but a Scandinavian fish not only can survive but also maintains a normal heartbeat for days, say researchers.
The crucian carp (Carassius carassius) has long been recognized as a champion survivor, thriving even in shallow ponds that freeze over during long Northern winters. These waters can turn into dead zones as creatures exhaust the oxygen in the water.
What researchers haven't known, though, is what strategy the carp follows for such a feat, says Jonathan A. W. Stecyk of Simon Fraser University in Burnaby, British Columbia. Turtles, the other vertebrates famed for toughing out times with no oxygen, reduce their heart functions to only about 10 percen