All of us have carbon monoxide in our blood. Our bodies produce it when hemoglobin in blood cells breaks down. People who smoke have elevated levels, though. And in this, they have something in common with elephant seals.
Both the seals and heavy human smokers turn out to have very high levels of dissolved carbon monoxide in their blood streams, new research finds. But while smokers acquire excessive levels of that dangerous compound from inhaling burning tobacco, elephant seals produce it naturally.
Elephant seals possess the highest known blood volume of any animal, the researchers told LiveScience, so the team decided to investigate whether their blood might be unique in other ways, too. They trapped 24 elephant seals found near Santa Cruz, California, and took blood samples to perform various measurements, including of carbon monoxide.
In humans who don't smoke, about one percent of hemoglobin is bound to carbon monoxide at any given time. In elephant seals, it averaged at about 10 percent. (Levels of 50 percent are deadly for humans.)
Elephant seals have the ability to cut off their blood supply to certain organs and extremities when holding their breath. The carbon monoxide might help prevent a condition called reperfusion, which sometimes occurs in humans when blood has been cut off for too long. The team isn't certain exactly why the seals have such high levels of carbon monoxide, Live Science says, but they suspect it might have something to do with helping the seals sustain prolonged deep water dives.