24 AUGUST: LONDON, UK – Squirrel monkeys are weighed on a scale during a photocall at London Zoo to promote the zoo’s annual weigh-in event. During the weigh-in, animals across the zoo have their vital statistics recorded including their height and weight and that information is then shared with zoos across the world to help zookeepers compare important information on thousands of endangered species.

(Photo credit: CHRIS J RATCLIFFE/AFP/Getty Images)