Beerwah, Australia ? “Crocodile Hunter” Steve Irwin was remembered today for his “great zest for life” at a public memorial service for the beloved conservationist and entertainer.

“We have lost a friend, a champion,” actor Russell Crowe said in a recorded tribute. “It will take some time to adjust to that.”

Prime Minister John Howard, among the 5,000 in attendance at the Australia Zoo for the ceremony, remembered Irwin for his love of Australia.

“Steve Irwin touched the hearts of Australians and touched the hearts of millions around the world in a very special way,” Howard said. “He did that because he had that quality of being genuine, of being authentic, of being unconditional and having a great zest for life.

“Throughout his all-too-short life he demonstrated a love for the two things that ought to matter more to all of us than anything else – his love of his family and his love of his country.”

A exuberant television entertainer and conservationist, Irwin, 44, died Sept. 4 when the barb from a stingray pierced his chest while he was filming for a TV show on the Great Barrier Reef. His family had a private funeral for him Sept. 9 at Australia Zoo.

The ceremony today featured footage of the hugely popular TV program that coaxed laughter from the attendees.

As expected, there was one empty seat at Irwin’s personal stadium – the one set aside for the late and hugely popular “Crocodile Hunter” himself. On the stage sat Irwin’s widow, American-born Terri, and their two children, Bindi, 8, and Bob, 2 – all dressed in Irwin’s favored khaki outfit. It was their first public appearance since Irwin’s death.

“Please do not grieve for Steve, he’s at peace now,” said Steve’s father, Bob Irwin. “Grieve for the animals. They have lost the best friend they ever had, and so have I.”

Later, Bindi Irwin told the crowd at the ceremony that she had the “best daddy in the world.”

“I will miss him every day,” she said.

Flags on the Sydney Harbor Bridge flew at half-staff today, and giant television screens were set up in Irwin’s home state of Queensland for people to watch the service. Three of Australia’s main television networks carried the hourlong ceremony, which was made available to U.S. and international networks and which family officials said could be watched by as many as 300 million people.

One of Irwin’s favorite Australian country singers, John Williamson, sang one of the naturalist’s favorite songs, “True Blue.”

At the end of the ceremony, Irwin’s utility vehicle, packed with camping gear and his favorite surfboard, was driven from the stadium – through an honor guard of Australia Zoo employees – to an encore singing of “True Blue.”

After the truck left the stadium, a group of employees spelled out Irwin’s catchword “Crikey” in yellow flowers on the ground.

Crowds began lining up Tuesday night for the start of the memorial service. Later, under sunny skies just before the start of the ceremony, dozens of television satellite transmission trucks were parked outside the zoo, a flora and fauna park owned by the Irwin family since 1970.

Irwin’s death set off an unprecedented outpouring of grief. Tens of thousands traveled to the zoo near Brisbane to drop off flowers and other mementoes, many of them signing khaki shirts instead of a condolence book.

Since Irwin’s death, his conservation charity Wildlife Warriors has seen a surge in donations and its Web site has received millions of hits.

As part of the public memorial entitled “He Changed Our World,” actress Cameron Diaz said in a video presentation that Irwin was incredibly popular in the United States.

“America just flipped for him,” Diaz said. “Every kid was in love with the idea of being him.”

Actor Kevin Costner said Irwin put himself “out there” for everyone to see. “He was fearless,” Costner said in the video tribute. “He let us see who he was. That is being brave in today’s society.”