Monica Schipper/Getty Images for Discovery, Inc.
Bindi posted an adorable throwback of her dad holding a koala and her as a baby. She thoughtfully wrote, "Thank you for always being my guiding light. ❤"
While her brother, Robert, also took to social media to remember his father with a picture of a Google Doodle that the company created to honor the Australian television personality.
"Thank you so much, @google for honouring dad with his own #GoogleDoodle all over the world. A perfect way to celebrate his birthday, sharing everything he did to make the world a better place," he wrote.
The Google Doodle was created to acknowledge "the life and achievements of my husband Steve Irwin, whose efforts to protect wildlife and wild places have been recognised as the most extensive of any conservationist. We are so proud that his legacy lives on, as that was his greatest wish," according to a blog post by his wife, Terri Irwin.