Staff at London Zoo got the measure of giant gorillas, plump penguins, and skinny stick insects at the zoo’s annual animal weigh-in on Thursday.

Zookeepers tempted squirrel monkeys onto scales with treats, totted up tarantulas, and used a curry-scented measuring stick to coax Sumatran tigers to stretch out.

Staff at the zoo, which is home to some 14,000 animals, will take several days to weigh and measure every mammal, bird, reptile, fish, and invertebrate in its care. The results go into a database that is shared with zoos around the world.

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"We record the vital statistics of every animal at the zoo — from the tallest giraffe to the tiniest tadpole," said Angela Ryan, the facility's head of zoological operations.

Ryan said an animal’s weight is vital information that can reveal whether creatures are healthy, and even which are pregnant.

"We have critically endangered animals here," she said. "It’s absolutely vital that we are managing them, managing their health, that we’re breeding them and breeding them well and we’re having healthy offspring that can breed on again."