The 44-year-old Irwin's heart was pierced by the serrated, poisonous spine of a stingray as he swam with the creature Monday while shooting a new TV show on the Great Barrier Reef, his manager and producer John Stainton said.

He said Irwin removed the barb from his chest but lost consciousness. "He pulled it out and the next minute he's gone," said Stainton, who saw videotape of Irwin's final moments.

A renown zoologist, and a conservationist, Steve Irwin faced some heat in 2004 when he was videotaped feeding a crocodile while holding this then 1-month old son, Bob. However, Australian authorities never pressed charges against Irwin.

"I am shocked and distressed at Steve Irwin's sudden, untimely and freakish death," Australian Prime Minister John Howard said. "It's a huge loss to Australia."

Steve Irwin played with crocodiles, komodo dragons, black mambas, and other deadly creatures, citing that if he was hurt, it was his own fault. However, this stingray incident may have been more of an accident than anything else.

Marine experts called the death a freak accident. They said rays reflexively deploy a sharp spine in their tails when frightened, but the venom coating the barb usually just causes a very painful sting for humans.

"He came on top of the stingray and the stingray's barb went up and into his chest and put a hole into his heart," said Stainton, who was on board Irwin's boat and saw the footage.

The tape shows Irwin pulling the barb before losing consciousness, Stainton told reporters Tuesday in the city of Cairns where Irwin's body was taken for an autopsy.

Crew members administered CPR and rushed to rendezvous with a rescue helicopter that flew to nearby Low Isle, but Irwin was pronounced dead when the paramedics arrived, Stainton said.

The tape of Irwin's final moments has been secured by Queensland state police as evidence for a coroner's inquiry, the producer said.

Irwin is survived by his wife Terri, daughter Bindi Sue, 8, and son Bob, who will turn 3 in December.