Penguins, capybaras, squirrel monkeys and a Vietnamese magnolia snail were among 10,000 animals measured at ZSL London Zoo’s annual “weigh-in” on Monday.

Every mammal, bird, reptile, fish and invertebrate was weighed, with some scales disguised in habitats to ensure animals hopped on.

Other animals are trained to step on the scales while devices for birds are hidden in doorways.

A Bolivian black-capped squirrel monkey was placed on a perch for the weigh-in while brother and sister capybaras Gizmo and Kiwi were lured onto the scales with food.

There are more than 10,000 animals at the zoo across 4,000 species.

The zoo’s smallest animals are Partula snails, which weigh less than one gramme.

Measurements are added to an information system shared with conservationists across the world to provide information on endangered species.

London Zoo’s animal operations manager Daniel Simmonds said: “Regular weigh-ins help zookeepers track the health of our animals – including insects like the magnolia land snails, the capybaras, and Humboldt penguins – and genuinely help us manage the care of these animals, who play a vital role in our global conservation efforts.”

The Zoological Society of London, which runs the zoo, celebrated its 200th anniversary this year.

The zoo opened in 1828.