Supercooled Blood

One of the mysteries of arctic life is how fish manage to survive in water so cold that their blood ought to freeze solid. In Hebron Fjord in Northern Labrador, the water at the bottom, 60 fathoms down, stays at -- 1.0DEGC. (28.94DEG F.) winter and summer. There are plenty fish in it, leading active lives, but when their blood is extracted and chilled, it freezes at --.8DEG to --1.0DEG C., nearly a full degree above the temperature in which they live normally.

Last week an expedition led by Dr. Per F. Scholander of the Woods Hole Oceanographic Institution landed at Boothbay Harbor, Maine after spending eleven weeks around Hebron Fjord trying to find out what keeps the fish from freezing. Dr Scholander had a theory that their blood "supercooled," remaining liquid because ice crystals never get a chance to start forming in it. Ordinary water behaves in the same way if it is carefully chilled without stirring. The blood of the fish of course, is in constant motion through their hearts and vessels, so Dr. Scholander reasoned that the fish must have some special system to keep it supercooled.

The summer's work with elaborate apparatus in a prefabricated laboratory did not solve the mystery; it added another mystery. Dr. Scholander found that arctic fish which live in the slightly warmer water at the surface will freeze solid if they are chilled in surface experiments to the temperature prevailing at the bottom. But when such fish were actually lowered into the cold depths, they did not freeze. Most of them were alive and active when hoisted back to the surface.

Dr. Scholander's tentative conclusion: the pressure at the bottom of the Fjord (about 160 Ibs. per sq. in.) works in some unknown way in combination with the cold to keep the fish swimming and feeding when they should be hunks of ice. We'll come up with the answer in time " he says, "but there's a factor missing somewhere."

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