An 81-year-old boater was in critical condition Thursday after a stingray flopped onto his boat and stung 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.

James Bertakis of Lighthouse Point was on the water with his granddaughter and a friend Wednesday when the stingray flopped onto the boat and stung Bertakis. The women steered the boat to shore and called 911.

Bertakis was apparently trying to remove the spotted eagle ray from the boat when he was stung, police Cmdr. Mike Oh said. The ray was approximately 3 feet across and 18 to 24 inches long, Oh said. Officials have kept the dead ray in case doctors need to examine it, Oh said.

Surgeons were able to remove some of the barb, and Bertakis, who also suffered a collapsed lung, underwent surgery late Wednesday and early Thursday, the Miami Herald reported on its web site.

Ellen Pikitch, a professor of marine biology and fisheries at the University of Miami, who has been studying stingrays for decades, said they are generally docile.

"Something like this is really, really extraordinarily rare," she said. "Even when they are under duress, they don't usually attack."