Dressed in the Irwin uniform of head-to-toe khaki, and sitting before a sea of floral tributes, the man who introduced the Crocodile Hunter to the world of reptiles — giving Steve a snake for his sixth birthday present — was visibly upset as he remembered his son. "Steve and I weren't like father and son," he said. "We never were. We were good mates. I'll remember Steve as my best mate ever."

Irwin died on Monday after a barb from a bull stingray pierced his heart off Batt Reef, near Port Douglas. His death was captured on film, showing him pulling the barb from his chest before losing consciousness, and the footage will form part of a police report to the coroner. Asked how he was coping with his son's death, Mr Irwin paused. "Tough," he said, holding back tears, "it's tough."

Mr Irwin said Steve's widow, Terri, was holding up extremely well, and was staying strong for the couple's children, Bindi, 8, and Bob, 2. "It's extremely hard for Terri and the children."

Australia Zoo staff told The Age Terri choked back tears in a message of support to staff on Tuesday night, speaking in a frail voice, barely above a whisper, on the zoo's two-way radio system: "Thank you everybody. We really appreciate it," she said. For the third day at Australia Zoo yesterday, a steady stream of visitors came to the entrance to pay tribute. On Tuesday, eight of Irwin's trademark khaki shirts scrawled with messages of condolence hung in front of the zoo, yesterday there were more than 20.

In between, hung flags from England, Ireland and the US, even a Liverpool football jersey, all bearing tributes to the Crocodile Hunter. Bob Irwin began Australia Zoo in 1970, when he, wife Lyn and Steve, then 8, moved to the Sunshine Coast from Melbourne. He said while it had been the force of Steve's personality and personal commitment that turned the zoo from a local tourist attraction into a global brand name, its work, particularly its conservation work through the Wildlife Warriors foundation, would continue under the Irwin name.

Irwin's antics, gleefully wrestling crocodiles, picking up venomous snakes, or diving with sharks, gave many the impression he was invincible. It was not an illusion shared by his father. "Over the years Steve and I have had a lot of adventures together," he said. "And there have been many occasions when anything could have gone wrong. Steve knew the risks involved in the type of work he was doing and he wouldn't have wanted it any other way."

The pair had discussed dying and had known tragedy five years ago when Lyn Irwin died in a car crash. Yesterday, Bob Irwin recollected a few close shaves he and Steve had shared. "But we both approached it in the same way: we made jokes of it. That's not to say we were careless, but we treated it like it was part of the job, nothing to worry about really."

He recalled camping trips with his young son, when they would wander off into the bush, just to talk. "That's when the mateship started, right back when he was six, seven, eight years old." But Mr Irwin's fondest memory of his son is a recent one, when he spent almost four weeks at Cape York Peninsula with his son and the family. "Steve was probably the best I've seen him for many years he was peaceful and he was not under stress and he was doing something he really loved doing. I won't ever forget those three or four weeks, I was very lucky."

As Bob Irwin spoke to reporters and well-wishers in front of the main entrance to the zoo yesterday, he expressed no surprise at the outpouring of emotion at his son's death. "There's never been anybody else I know of that had the personality that Steve had, and the strength and the conviction of what he believed in. He was such a strong person that people all over the world believed in him."