Bindi Irwin has revealed the gender of her first baby and said it is the same size as a “hatchling Aldabra tortoise”.

The TV star and daughter of the late Australian star Steve Irwin, known as The Crocodile Hunter, shared the news that she and husband Chandler Powell are having a girl on Instagram.

Alongside a picture of herself and Powell kneeling next to a large tortoise, she told her nearly four million Instagram followers: “Baby girl, you are our world.

“Our beautiful daughter is now about the same size as a hatchling Aldabra tortoise and is as healthy as can be. We can’t wait for her arrival next year”.

Powell shared the same photograph, captioning it: “Our little girl and my beautiful wife are my entire world. I’m so excited to meet our daughter when she’s born next year and to see the incredible person she will grow up to be”.

Irwin and Powell got married in March this year at Queenland’s Australia Zoo, where Irwin and her family live, hours before the country banned weddings attended by more than five people.

During the ceremony, they lit a candle in memory of her late father Steve, who was killed by a stingray in September 2006, when she was eight.

The couple announced news of their baby earlier in August on Instagram, posting a picture of them holding up a tiny Australia Zoo uniform writing: “Baby Wildlife Warrior due 2021”.

According to the official Australia Zoo website, Aldabra tortoises are native to the “islands of the Aldabra Atoll and Seychelles, off the coast of Africa”.

They estimate that the adult species can weigh in at around 660 pounds (300 kilograms).