Keepers at London Zoo have discovered why a male sloth seemed reluctant to mate with its arranged partner - his "girlfriend" Sheila turned out to be male.
Sheila was brought to the zoo in the hope of breeding the first two-toed sloths there for more than a century.
But the patter of tiny feet was not forthcoming and an ultrasound scan revealed why.
The sloth - a notoriously hard animal to sex - was not female.
Now Sheila has been shipped out and replaced with playful three-year-old Marylin.
And this sloth is most definitely a lady.
Senior zoo keeper Lucy Hawley said: "Two-toed sloths are very secretive creatures so we are never quite sure what they're up to but we like to encourage them to meet as often as possible.
"It would be amazing if we were to have a two-toed sloth baby at London Zoo.
"We haven't bred them since the 1800s so it would be a very special baby."
Prince, a shy 25-year-old, is yet to mate with his new partner.
But keepers are encouraging him to move around the rainforest-style enclosure by leaving trails of fragrant herbs for him to follow.