Jessica donned a red mask to fit with the masquerade and costume theme of the birthday bash as she belted out hits like Burn as well as new track Up Down and performed a cover of Cindi Lauper's Time After Time in honour of the Irwins conservation efforts.

But the real thrill for the crowd came just before noon when Bindi entered the Crocoseum with her mum and brother.

Hundreds of Bindi and Bob look-alikes cheered and watched a special video message from the Australia Zoo staff for the international star.

After a quick happy birthday, the cutting of one very pink cake and three hip-hip-hoorays, Bindy left the Crocoseum after delivering her conservation message, asking people to sign a petition to save Steve's place from a an application to mine the Steve Irwin Wildlife Reserve.