On Wednesday (August 21) it was time for London Zoo's keepers to find out which animals have been eating too much or not getting enough exercise during the annual weigh in.
It was easy to get some of the creatures onto the scales. An African bull frog sat sedately in the bowl as keepers recorded his weight at 400g. The tiny bright green waxy monkey frog sat in a small spoon to be weighed, he was ten times lighter at just 40g.
The annual job also sees keepers measuring the height of their animals. No small task when it came to the tiger enclosure.
Morsels of raw meat were dangled in front of Jae Jae, the Sumatran tiger to get him to stand up and be counted. He measured 6 foot 6 inches on the giant measuring tape in his enclosure.
Keeper Paul Kybelt said it's very important to keep an eye on the weights and heights of the zoo's inhabitants.
"If we have no idea how heavy they are, or if their weight is fluctuating on a daily or weekly basis, it could be some kind of medical condition. If we don't bother weighing them then how do we really know?" he said.
The information goes into a global data base to allow zoos around the world to monitor animals health.
Keeper Angela Ryan said it is also useful to compare weights and measures of zoo animals against those in the wild.
"Because obviously animals in captivity can sometimes put on a little bit more weight being around humans. Sometimes you like to give animals, you know, the food that they want, so we have to be very careful and very strict with their diets to make sure they are fit and healthy and so by having a weigh in we can compare them to their wild friends," said Ryan.
Some of the animals were a little shy to get onto the scales - perhaps they knew they'd over indulged? Tammy the tree anteater had to be coaxed onto the scales with the temptation of a cup full of food. She weighed a respectable 6.8 kg in the end.
One of the zoo's heavier residents, Noemi the camel weighed 625 kg.
Presented by Adam Justice