An 81-year-old boater was in critical condition Thursday after a stingray flopped onto his boat and stabbed him, leaving a foot-long barb in his chest, authorities said.

"It was a freak accident," said Lighthouse Point acting fire Chief David Donzella. "It's very odd that the thing jumped out of the water and stung him. We still can't believe it."

Fatal stingray attacks like the one that killed "Crocodile Hunter" Steve Irwin last month are rare, marine experts say. Rays reflexively deploy a sharp spine in their tails when frightened, but the venom coating the barb usually causes just a painful sting for humans.