It’s that time of the year again for some of the animals at ZSL London Zoo who have had their annual measurements taken.

Ham & High: Maggie the giraffe stands next to a specially erected ruler, to see if she has grown over the last year. Picture: London Zoo/Tony MargiocchiMaggie the giraffe stands next to a specially erected ruler, to see if she has grown over the last year. Picture: London Zoo/Tony Margiocchi (Image: TONY MARGIOCCHI)

Meerkats, bullfrogs, monkeys, and giraffes were among the 592 species weighed and measured over the last week. Even the snakes hit the scales. Oni the okapi was the heaviest at 247kg.

The zoo's keepers spend hours throughout the year recording the heights and weights of all 19,000 species in their care. It helps give them an idea about their health and wellbeing.

Each measurement is added to the Zoological Information Management System, which is shared with zoos throughout the world to help keepers compare information on endangered species.

ZSL London Zoo's assistant curator of mammals, Teague Stubbbington said: "We have to know the vital statistics of every animal at the Zoo - from the tallest giraffe to the tiniest ant.

Ham & High: Dracula the Meerkat gets distracted by a staff member while being weighed. Picture: London Zoo/Tony MargiocchiDracula the Meerkat gets distracted by a staff member while being weighed. Picture: London Zoo/Tony Margiocchi (Image: TONY MARGIOCCHI)

"It helps to ensure that every animal we look after is healthy, eating well, and growing at the rate they should - weight is a particularly important indicator of health and wellbeing.

"A growing waistline can also help us to detect pregnancies, which is so important as many of the species at ZSL London Zoo are endangered and part of international breeding programmes."