Keepers at Bristol Zoo had quite the surprise when they discovered their moody adolescent boy gorilla was actually a girl.
Kukena has spent the last six years being treated as a boy because keepers didn't want to invade her personal space.
She was born 27 September 2011 to mum Salome and the troop's silverback Jock. But only recently the animal team have noticed she's had her first time 'on heat' and her body has started showing signs she's a girl.
But instead of being an embarrassing slip-up the zoo is celebrating!
There are far fewer female Western lowland gorillas than males in captivity, so Kukena has helped boost their numbers. Keeper say the discovery won't change how they look after the troop of seven gorillas at Bristol Zoo
When ITV West Country reported about Kukena's birth, keepers told us they'd chosen the name without girl or boy connotations because they weren't sure which she was.
Kukena means 'love' in the language of a local tribe where Western Lowland gorillas are found in the Congo.
The animal team will now discuss whether Kukena should move to another zoo in the next couple of years to continue the breeding programme for the Critically Endangered species.