The signs usually posted around coastal communities in Australia warn swimmers not to dive in during "stinger season," but those warnings weren't enough to save a 17-year-old boy who died Monday, a week after a rare attack from an extremely poisonous jellyfish in Queensland. Authorities say the teen was swimming at a beach in Bamaga, in Cape York, on Feb. 22 when he was stung by a box jellyfish, a marine creature shaped like a box with long, barbed tentacles filled with venom, per the BBC, which notes that this jellyfish's sting can lead to paralysis and cardiac arrest in the victim and prove fatal. 9News identifies the teen as Tommy Johnson, who police say died Monday at Townsville Hospital after being taken off life support about a week after the incident.
It was the nation's first known death from a box jellyfish since 2006. "Unfortunately, that [previous] fatality also occurred in Bamaga," a marine biologist tells ABC Australia. Local health official Dr. Marlow Coates says there have been recent sightings of "both box jellyfish and jellyfish that cause Irukandji syndrome in our waters," per 9News, which notes that someone who gets stung by one of these creatures should expect immediate, intense pain. The sting should be treated with vinegar—not fresh or salt water, which can make things worse. You also shouldn't try to pry off the tentacles or rub the site of the sting. Or, you could avoid this type of injury altogether by heeding Coates' warning: "If you don't have a protective suit and you know there could be stingers or jellyfish in the water, just don't go in." (Read more jellyfish stories.)