"These are the most venomous animals in the world based upon fatalities over the last 30 years," said study author Angel Yanagihara, a biochemist at the University of Hawaii at Manoa.
float in the waters from Australia all the way to Vietnam. The ethereal creatures can sport 6.5-foot (2-meter)-long, ribbonlike tentacles that often attach to swimmers or scuba divers and inject venom through hundreds of thousands of microscopic, harpoonlike barbs, Yanagihara said. (Gallery: Amazing Photos of Jellyfish)
"All that venom then seeps into the bloodstream. With each beat of your heart it's being pumped around your circulatory system," she said.
The deadly stings can kill quickly by causing cardiac arrest. Until now, doctors had no effective treatments to counteract the venom.
Instead, they would treat a cascade of symptoms, such as high or low blood pressure, and hope for the best, she said.
"It's usually a race against time where the clinician is treating symptoms as they crop up," Yanagihara told LiveScience.