London Zoo carried out its annual weigh-in on Monday, measuring more than 10,000 animals across 4,000 species as part of routine health monitoring. Keepers used a mix of coaxing, training and disguise to get penguins, capybaras, squirrel monkeys and even tiny snails onto scales, since the exercise helps track development, spot pregnancies and flag health issues early.

Techniques varied by species: capybaras Gizmo and Kiwi were lured with food, Bolivian squirrel monkeys were tempted onto scales disguised as a climbing frame, and Humboldt penguins were enticed with fish before returning to play. The zoo's smallest residents, Partula snails, weigh under a gram, while insects such as katydids and Vietnamese magnolia snails were also recorded. The data feeds into a global conservation database, and the event comes as the Zoological Society of London, which runs the zoo, marks its 200th anniversary this year.