Unusual Heart Valve Lets Crocodile Remain Under Water for Hours

An unusual heart valve in crocodiles that has puzzled scientists for nearly 200 years has finally been explained, and the finding may reveal how crocs can stay under water for hours. The valve bypasses the lungs when they are empty, diverting and recirculating what little oxygen is in the blood to the animal’s most vital organs, researchers report in today’s Nature. The Swedish and Australian team studied a common saltwater crocodile, focusing on a valve in its right ventricle called a cogged-teeth valve. Mimicking conditions under water, the researchers prompted the notched valve to close off an entry to the artery leading to the lungs, diverting blood back into the bloodstream.

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--Compiled by Times medical writer Thomas H. Maugh II