Naturally produced carbon monoxide - a noxious gas that is deadly at high concentrations - has been discovered to be part of elephant seals' blood in surprisingly high levels, a new study reported.
The amount of carbon monoxide found in the blood of these large mammals can be compared to that in smokers who ingest 40 or more cigarettes each day, Live Science reported.
The unexpectedly high levels of the gas in their blood could be to protect the animals from injury when they dive to extreme depths in search of food, researchers said.
However, scientists have claimed to be uncertain why elephant seals have this amount of gas.
In humans and animals, carbon monoxide is a byproduct of the breakdown of hemoglobin, which carries oxygen in red blood cells throughout the body, said study leader Michael Tift, a comparative physiologist at the Scripps Institution of Oceanography at the University of California, San Diego.
"Elephant seals are known to have the highest blood volume of any mammal, so we knew there was the potential for producing a lot of carbon monoxide," Tift told Live Science. "When we looked into the levels of carbon monoxide in the blood, we suspected there could be a lot."
Even though the mammals are inflicted with elevated levels of carbon monoxide in their bloodstreams, researchers said the concentration of the gas is not so high.
"The levels in elephant seals are not high enough to inhibit oxygen transport or lead to carbon monoxide poisoning," Tift said.
According to Live Science, the researcher and his colleagues sampled 24 elephant seals, ranging in age from pups to juveniles to adults, at the Año Nuevo State Reserve near Santa Cruz, California.
"Elephant seals will shut off blood to specific organs and tissues as they are diving," Tift said. "Recently, we found that low levels of carbon monoxide can be therapeutic in treating certain conditions where blood has been shut off to muscles."
After sustained periods of oxygen deprivation, blood returns to tissue, prompting carbon monoxide to protect elephant seals from reperfusion injuries.
"We can't say for sure that the carbon monoxide is therapeutic for elephant seals, but it definitely has the potential," Tift said. "If they didn't have this high level of carbon monoxide, there's a chance we would see injuries from reperfusion."
Other diving and non-diving animals, including sea lions, penguins and terrestrial birds are being studied to test the hypothesis, the researchers said.
"We want to know, is high carbon monoxide found in all marine mammals? Is it found in deep divers, or both divers and non-divers?" Tift said.
The results of the new study were published online today (May 14) in the Journal of Experimental Biology.
