The carbon monoxide level in an elephant seal is equal to that of smokers who ingest 40 or more cigarettes every day, according to a University of California, San Diego study.
Researchers said that the presence of surprisingly high levels of naturally produced noxious gas in their bloodstreams could be to prevent injuries when animals plunge to extreme ocean depths for food.
"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."
Study leader Michael Tift, a comparative physiologist at the Scripps Institution of Oceanography, said that in humans and animals, carbon monoxide is a by-product of the breakdown of haemoglobin, Huffington Post reports. Lower amounts of carbon monoxide are associated with health benefits. CO lessens inflammatory responses and cell death due to heart attack and stroke.
Tift said that although the large mammals have been discovered with unexpectedly high levels of the gas in the blood, the concentration are not high enough to hinder oxygen transport or lead to carbon monoxide poisoning.
For the study, the researchers observed 24 elephant seals, ranging from pups to adults, at the Año Nuevo State Reserve near Santa Cruz, California.
Elephant seals shut off blood to specific organs and tissues when they are diving. The restoration of blood flow to the tissues can lead to additional damage that is termed as reperfusion injury. Researchers suspect that carbon monoxide could be behind the prevention of reperfusion injuries in elephant seals.
"We found that low levels of carbon monoxide can be therapeutic in treating certain conditions where blood has been shut off to muscles," Tifts said.
In the study, the researchers did not determine as to how carbon monoxide is beneficial for elephant seals. Tift said that if the mammals did not contain higher levels of carbon monoxide, there could be more instances of injuries from reperfusion.
Further studies to test the hypothesis are being conducted on other diving and non-diving animals including sea lions, penguins and terrestrial birds. Tift said that whether higher amounts of carbon monoxide is found in all marine animals, deep divers and non-divers will also be studied.
The findings are published online in the Journal of Experimental Biology.
