(CNN) -- Imagine the Beatles going on without Paul McCartney. Or *NSYNC without Justin Timberlake. Or Van Halen without David Lee Roth (or Sammy Hagar, or that other guy).
The Wiggles are Anthony Field, blue; Sam Moran, yellow; Murray Cook. red; and Jeff Fatt, purple.
Young fans of the children's rock group the Wiggles -- and more important, their parents -- faced a similar experience when singer Greg Page, the Yellow Wiggle in the brightly colored group, left last November for health reasons.
On Tuesday, the group released "Getting Strong" in the United States, its 28th DVD and the first without Page. They're also getting ready to set out on their third U.S. tour of the year.
The Wiggles, as most parents know, are as ubiquitous as sippy cups and blankies in the preschool set with catchy songs like "Hot Potato," and "Fruit Salad" that can wedge themselves into the brain for days.
The group started as a class project for childhood education students Page, Anthony Field and Murray Cook, who recruited Jeff Fatt to help them with a few songs.
Fast-forward 16 years and you've got a global entertainment empire that's sold more than 15 million DVDs and videos, 2.5 million CDs and 7 million books in the United States alone. They've also opened "Wiggles World" sites at three Six Flags amusement parks in the United States. Watch Sam the Yellow Wiggle in his DVD debut »
In Australia, the Wiggles are more like an institution than a rock band. The government named them Australian Exporter of the Year in 2005; they were the top-earning Australian entertainers for the last two years and were voted the third most trusted Australians (behind a famous burn doctor and a cancer researcher) in a Reader's Digest poll earlier this year.
Each of the characters can be identified by the color of his shirt and a personality quirk. Blue Wiggle Field loves to eat healthy food, Red Wiggle Cook invents things and plays guitar and Fatt, the Purple Wiggle, tends to nod off and must be roused with a shout of "Wake up, Jeff!" Page performed magic tricks and drove the Big Red Car, the group's primary mode of transportation.
So Page's departure raised big questions for the band.
"We did do some soul-searching and discussions, but it didn't last very long," Cook said. "The three of us were pretty keen to continue. But it was really planned out how we would go about it."
Page handed over his yellow shirt, or skivvy as they call it in Australia, to his understudy and longtime Wiggles dancer Sam Moran.
"The way we really went about it was we wanted to be honest with people and just tell them what happened. That Greg was sick and couldn't continue and that Sam was the new Wiggle," Cook said. "And I think if you're honest with your audience they're fairly accepting, really." See I-Reporters show their love for the band »
Moran said he gets recognized as the Yellow Wiggle once or twice a day and that it's a little weird "when you go to the supermarket and see your face on the side of a box of some breakfast cereal or something."
Moran said fans have been great and really welcoming.
"It's been a much more gradual thing for me because being the understudy for Greg and filling in more and more as his condition got worse, so it's been a much more gradual transition from my perspective, but it's fantastic, we just have a ball," he said.
Page has a chronic condition called orthostatic intolerance that, while not fatal, causes weakness, fainting and made it impossible for him to keep up with the group's hectic touring and recording schedule.
He's not doing interviews, but a spokeswoman for the Wiggles said he was doing much better than he was a year ago.
Cook said they keep in touch, but their travel schedule makes it hard.
"He's been up and down really with his illness and he says some days are better than others, but the last time we saw him he was looking quite well," Cook said. "I know his doctor has changed his medication around a bit and I think he's managing quite well."
The transition was a challenge for Page and the rest of the band, Field said.
"We'd be about to go on stage and Greg would take a turn and faint and Sam would have to step in, so it was very unsettling ... not knowing how Greg's condition was in the last year or so," he said.
Field said it helped that they knew Moran so well.
"Sam's been a mate of ours for years and of Greg's, and stepped in for Greg many times so it wasn't hard from an entertainment point of view," Field said.
But he said they still give Moran a hard time.
"We just constantly tease him about being the new guy. If we're still around in 15 years, we'll still be teasing him about being the new guy," Field said.
Field said they let Moran get behind the wheel of the Big Red Car, but they put learner plates (for new drivers) on it before his first official gig.
Jodi Grundig, a writer for the blog "Mom's Favorite Stuff," said she didn't know how her 3-year-old daughter Isabelle would react when she saw a review copy of the DVD.
"Before I put the video in I told her this was with a different Yellow Wiggle, so she kind of expected it," Grundig said. "She didn't really comment on it, but when she wants to watch that video she says 'I want to watch the one with Sam.'"
The Wiggles are working on a new television series with Moran that's due out next year, but in the meantime, Page is still wiggling away every morning on the Disney Channel.
Grundig said that's confused Isabelle a little bit.
"I told my daughter that Greg's not on any more because he's sick, but then when the Disney Channel comes on she says 'Look, Mommy, Greg's not sick any more'," Grundig said. "I think she thought that by sick it meant he had a tummy ache or something."
Laura Chin had a conversation with her 5-year-old daughter, Alexis, before taking her family to see the band in Detroit, Michigan, this summer.
"I also explained to her that Sam was a Wiggle before, so when we saw him in the old videos I would say 'there's Sam. that's the new Yellow Wiggle; he's the one we're going to see'."
Chin said her 2-year-old "Wiggle fanatic" son Daniel didn't notice the difference, and Alexis didn't have a problem with the change.
"She would have liked to see Greg but she was glad he was taking time off to get better." E-mail to a friend
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