Stonefish: The Fish with the Deadliest Sting

In the shallow waters near Cairns in July 2010, a swimmer stepped on what looked exactly like a lump of coral and collapsed within thirty seconds. That wasn’t coral-it was a stonefish, hidden so perfectly in sand and algae that even scientists sometimes need a second look. Eleven dorsal spines fire upward automatically, each sharper than a hypodermic needle and dripping with venom so potent that it can cause paralysis, heart failure, and death. Lifeguards keep special anti-venom kits just for stonefish at every northern Australian beach, because after those spines inject their dose, a human can die in under an hour.