Thousands of animals have been flexing their muscles and jumping on the scales at the annual weigh-in at London Zoo.
From the smallest snails and penguins right through to lions and tigers, all animals have been measured and weighed.
It took some trickery to get the critters to behave - mostly involving food.
The lions and tigers were lured to stretch on their tip-toes to get as tall as possible, while the penguins waddled on to the scales quite sedately.
With more than 17,000 animals, the mammoth task is carried out on a yearly basis by zookeepers as a way of keeping track of every animal's health and wellbeing.
"This information helps us to monitor their health and their diets and by sharing the information with other zoos and conservationists worldwide, we can use this knowledge to better care for all our animals," says zoological manager Mark Habben.