As fans and media mourned the death of the irrepressible naturalist who became Australia's best-known ambassador, the premier of northeastern Queensland state, where Irwin lived and died, offered him a state funeral.
Australian movie star Russell Crowe, Prime Minister John Howard and Foreign Minister Alexander Downer meanwhile joined thousands of stunned fans in paying homage to Irwin, who died when a stingray's barb pierced his heart as he filmed
an underwater documentary off Northern Queensland.
Newspapers around the world carried front-page reports on Irwin's grisly death and on his life as a passionate environmental crusader and global media star.
"He was the Australian we all aspire to be," Irwin's friend Crowe said from New York. "He was and remains the ultimate wildlife warrior. I believed in him. I'll miss him.”
The attack as Irwin snorkelled about one metre above the ray in shallow water off the town of Port Douglas was caught on film by a cameraman who was swimming ahead of the creature, police and Irwin's producers said.
Film "shocking"
Irwin's longtime friend and "Crocodile Hunter" television producer John Stainton, who had gone out to sea with Irwin, said the film of the deadly encounter was "shocking".
"I did see the footage and it's shocking," Mr Stainton told reporters in Cairns. "It's a very hard thing to watch because you're actually witnessing somebody die ... and it's terrible.
"It shows that Steve came over the top of the ray and the tail came up, and spiked him here (in the chest), and he pulled it out and the next minute he's gone," he said.
While stingrays rarely attack humans - only three other deaths by stingray have reportedly been recorded in Australia and only 17 worldwide – their 20-centimetre venomous barbs can be lethal.
Coroners in Cairns in the north-eastern state of Queensland carried out an autopsy on Irwin last night and initial results confirmed that he died after being speared in the chest by the ray's barbed tail while he was filming an underwater documentary on the Great Barrier Reef.
"We're not going into the detail but there's definitely no surprises.
Everyone knows how he died," a police spokeswoman said of the post-mortem examination, details of which will be released at a coroner's inquest.
It remained unclear whether the ebullient Irwin died of blood loss, a heart attack induced by the blow or from the ray's venom, media reports said.
Coroners have a copy of the video and will examine it ahead of the inquest, the date of which has yet to be set, a Queensland police spokeswoman said.
Funeral
The body of Irwin has been flown to the Sunshine Coast from far north Queensland.
While no details of funeral arrangements for Irwin have been revealed, Queensland Premier Peter Beattie said the man known around the world for his ebullience, thick Aussie accent and khaki bush gear, would get a Queensland state funeral if his widow Terri requested one.
"He will be remembered as not just a great Queenslander, but a great Australian," Mr Beattie told Channel Seven news, adding that Irwin was better known in the United States than Prime Minister John Howard.
Mr Stainton, who was accompanying the body, said Irwin's funeral arrangements would be left to the family, but said a state funeral would be a fitting tribute to Irwin's contributions to Queensland and Australia.
Irwin is survived by his wife Terri and their children Bindi, aged eight, and Bob, two.
Death tops global news
The Croc Hunter harpooned by a stingray was the top story in America and other corners of the world, with America's leading morning TV show, Today, NBC and CNN among those dedicating their lead news stories to the Irwin tragedy.
Animal Planet, the US cable TV channel where Irwin documentaries are a staple of the programming, also abandoned its schedule and ran a marathon of Crocodile Hunter programs.
In Britain, newspapers ranging from The Guardian to Rupert Murdoch's tabloid, The Sun, ran prominent stories on the fallen Crocodile Hunter.
The Guardian wrote how Irwin's passing had been compared by Australians to the death of Princess Diana, while stories were also prominent in newspapers across Europe, Asia, South America and South Africa.
The US Embassy has sent its sympathies to Steve Irwin's family, describing the late Crocodile Hunter as an unofficial Australian ambassador.
In a brief statement, the US mission said: "Our hearts go out to his family at this difficult time. As the Crocodile Hunter, Steve Irwin was in many ways an unofficial Australian ambassador to the United States.
"With his humour and irrepressible sense of adventure, he represented those things our citizens find most appealing about Australia and its wonderful way of life.
"Americans everywhere join Australians in celebrating the legacy he leaves of deep admiration for the wonders of Australia's unique environment and animal life. He will be enormously missed."
Zoo becomes shrine
Hundreds of mourners have turned out to pay tribute to Steve Irwin at his world famous wildlife park.
Some too distressed to speak, fans of all ages today laid flowers and other mementoes outside the entrance of Australia Zoo at Beerwah, north of Brisbane.
Meanwhile Prime Minister John Howard told federal parliament: "Steve Irwin's death yesterday in bizarre, tragic, and in some respects quintessentially Australian circumstances has not only shocked and horrified the people of Australia but it has brought forth an outpouring of grief and an outpouring of emotional expressions of regard for this remarkable man around the world,"
The prime minister described Irwin as a talented showman who used his skills for good.
Labor leader Kim Beazley also paid tribute to the famous crocodile hunter and said Irwin was "the quintessential Aussie larrikin".
"His infectious, larger-than-life persona, his willingness to embrace any number of fierce and venomous creatures, and his signature catch-cry `crikey' endeared him to the world.
"As somebody who loves language, I am sincerely grateful to him for reintroducing that marvellous word into common usage."
Queensland Premier Peter Beattie said the state government was in talks with Mr Irwin's family about possible ways to honour him and could have a national park named after him.
"We will make sure there is some form of national recognition," Mr Beattie said.
'Don't demonise rays'
Sydney Aquarium's senior aquarist Grant Willis said the accident in which Mr Irwin died was an extremely rare occurrence that should not destroy the placid animal's reputation.
"I'm sure he (Mr Irwin) would be devastated if people now demonise all these stingrays, because its just an absolute freak accident," Mr Willis said.
"Hopefully, we'll try to educate people that rays are generally a gentle animal. Just leave them alone and you won't get hurt."
Meanwhile marine and toxicology experts have ruled out envenomisation – venom – as contributing to Irwin’s death, instead comparing the way he died to being stabbed in a vital organ with a dagger or pair of scissors.
Dr Geoff Isbister, a clinical toxinologist at the Mater Hospital in Newcastle, said a stingray's tail was "just like a dagger", which would have caused major tissue trauma and massive internal bleeding.
"What happened to Steve Irwin is like being stabbed in the heart," Dr Isbister said. "It has little to do with the venom and all to do with the trauma caused by the barb of the stingray.”