The siblings posted touching tributes to their father on what would've been his 60th birthday.
Bindi and Robert Irwin are remembering their dad. The siblings each took to Instagram on Tuesday to pay tribute to their late father, Steve Irwin, on what would've been his 60th birthday. Steve died in 2006 after being pierced in the chest by a stingray barb.
Bindi, 23, posted a pic of her and her dad smiling as they sported matching khaki shirts.
"Happy Birthday to the greatest dad and Wildlife Warrior," Bindi began the caption, before revealing how she planned to mark the late Crocodile Hunter star's birthday.
"Today I’ll watch The Crocodile Hunter with Grace Warrior and share stories about her incredible Grandpa Crocodile," she wrote of watching Steve's TV series with the 10-month-old daughter she shares with her husband, Chandler Powell.
Bindi concluded, "I love you with all my heart. Your legacy lives on."
For his post, Robert shared a photo of himself giggling in glee while riding a motorbike with his dad.
"Happy birthday Dad. I love you and I miss you more every single day," he captioned the pic. "My earliest memories are my fondest, thanks to you. Hanging on tight to the handlebars of the motorbike, when you’d take Bindi and I on your morning lap of the zoo - before going to get ice cream for breakfast."
"Every minute spent with you was a blessing," Robert added. "I’m gonna ride that lap on your old motorbike this afternoon."
Robert appeared on Monday's episode of The Kelly Clarkson Show, and revealed how he is able to honor his dad's legacy on a more full-time basis since turning 18.
"It is definitely really exciting. Wildlife conservation is everything to us, protecting our world wildlife. And now turning 18, I get to be more stuck in with all of the different conservation work that we do around the world," he said. "It really is a big honor for me to get to work full-time, and to [begin] this wonderful new chapter of life. It's really, really exciting. I'm very, very proud definitely."
When ET spoke to the Irwins last month, the family shared how little Grace takes after her late grandpa.
"I think she's got that determination that Steve had and that connection with wildlife," Terri Irwin, Steve's widow, said of her granddaughter. "Because it is weird to see animals just gravitate to her. So she'll go out in the morning in the stroller, and all the kangaroos just gather around her like they're having a meeting."