STEVE IRWIN, who has died during underwater filming aged 44 after a stingray barb pierced his heart, was known through his documentaries on the cable TV channel Animal Planet to some 500 million people in more than 120 countries. As the exuberant, golden-haired, khaki-wearing and apparently fearless Crocodile Hunter, he got very close to — and even wrestled — numerous apex predators. His unscripted narration was punctuated with “Crikey!” and “ Look at this beauty!” Many called him a thrill seeker, but he called himself a wildlife warrior. He was in fact a highly knowledgeable natural historian, whose mission was to educate people by enthusing them. “If you can’t get wilds into people’s hearts”, he said, “then we haven’t got a hope in heck of saving them — because people don’t want to save something they don’t know.”

Stephen Robert Irwin was born in Melbourne in 1962. When he was 8 the family moved to Queensland, where they started the small Queensland Reptile and Fauna Park in Beerwah on the Sunshine Coast. Irwin was involved from an early age: he helped to look after the reptiles, having been given a scrub python for his sixth birthday (for which he started to catch fish and rodents) and by the age of 9 was jumping into rivers at night and catching crocodiles with his bare hands. In time he became one of the stars of the Queensland government’s rogue crocodile relocation programme. Many of the crocodiles were relocated to the family’s park, which was expanded in 1987.

Four years later Irwin took over management of the park, renaming it Australia Zoo, and the following year married Terri, who had been a visitor to the park. They went on a crocodile-trapping honeymoon in northern Australia, which — because of a chance meeting with with his old friend John Stainton, a television producer — became the first episode of The Crocodile Hunter series.

Ten one-hour episodes were made over the following three years, and more than 50 in total. Irwin was typically to be seen crawling towards wild crocodiles, snakes, goannas and spiders, among many other animals. “I would never blame an animal if it bit me, that is for sure,” he said to one interviewer, “because I’m at fault, not them”. He later estimated that he had been bitten more than 1,000 times. He was sanguine as ever when his leg was “ chomped” by a saltwater crocodile and needed 12 stitches. “I heal so quickly,” he said. “I tell you what, if you cut my arm off I would grow a new one.”

Irwin in fact felt rather more fear than he showed, and was particularly edgy in the presence of parrots. “For some reason parrots have to bite me. That’s their job. I don’t know why that is. They’ve nearly torn my nose off.”

The popularity of Irwin’s programmes boosted business in reptile parks around Australia. Conscious of the educational impact he could have, he frequently reminded his public that many of the animals — including 17 of the 23 crocodile species — were rare or endangered. He fulfilled his mission as an environmentalist by creating International Crocodile Rescue and the Steve Irwin Conservation Foundation — which later became an independent charity and was renamed Wildlife Warriors Worldwide.

As a recognised ambassador for conservation he was invited to become the face of the Australian Customs quarantine publicity campaign, part of the effort to keep animal and plant diseases out of Australia. He and his slogan “Quarantine matters! Don’t muck with it!” brought about a 25 per cent increase in the number of people volunteering information about potential breaches; it was the Australian Quarantine and Inspection Service’s most successful campaign.

His zoo, meanwhile, was thriving. Having undergone Irwin’s imaginative improvements — including the addition of an Animal Planet Crocoseum, rainforest aviary and Tiger Temple — it attracted the US Olympic track team during their visit to Australia for the Sydney 2000 Olympics, and was voted Queensland’s top tourist attraction in 2002. Its success was helped by Irwin’s appearances in the Eddie Murphy film Dr Dolittle 2 and another, weakly plotted, feature film, The Crocodile Hunter: Collision Course (2002), which nevertheless won the best family feature film award for a comedy film at the Young Artist Awards.

But Irwin had a few lapses of judgment: in 2004, during a public show at his zoo he “did a Michael Jackson” and fed a chicken to a crocodile while holding his baby son Bob in his other arm 3ft away. It caused outrage — and prompted the Queensland government to ban children and untrained adults from entering crocodile enclosures — but Irwin vigorously defended himself, saying that the child was in no danger, and that it equated to other children learning to swim.

Then, in June 2004, Irwin was said to have breached an Australian law prohibiting people from getting too close to Antarctic wildlife in filming whales, penguins and seals. In response to the outcry a special edition of Crocodile Hunter, entitled Crocodiles & Controversy, was made to explain both incidents.

Appearances on Larry King Live (2004) and The Tonight Show with Jay Leno (2006) helped him to win back some support, and Irwin had just signed a deal with Warner Brothers and IMAX in America to make an IMAX film next year. He was filming an underwater documentary Ocean’s Deadliest on the Great Barrier Reef, when he died.

Irwin owned land in Australia, Vanuatu, Fiji and the US. He was a fan of Essendon in the Australian Football League, and loved mixed martial arts competitions. He supported the conservative Liberal Party, and once described the Prime Minister, John Howard, as the “greatest leader in the entire world”. Howard returned the favour on hearing of Irwin’s death, calling him “the genuine article . . . he took risks, he enjoyed life, but he brought immense joy to millions of people, particularly to children”. Among Irwin’s legacies is Elseya irwini, a new type of snapping turtle he discovered on the coast of Queensland. He was named Tourism Export of the Year in 2004.

Irwin’s death in a stingray attack is thought to be only the second known case in Australia. Stainton has said that Irwin’s eight-year-old daughter Bindi, whose new TV show will appear in January, will succeed him as wildlife warrior.

He is survived by his wife, son and daughter.

Steve Irwin, naturalist, environmentalist and TV presenter, was born on February 22, 1962. He died on September 4, 2006, aged 44.