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

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.

A monkey is placed on a perch by a zoo keeper to be weighed
A Bolivian black-capped squirrel monkey is weighed during the annual weigh-in (Yui Mok/PA)

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.

A group of penguins are weighed by a zoo keeper at London Zoo
The Humboldt penguins are trained to step onto the scales at the annual weigh in (Yui Mok/PA)

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.

ZSL London Zoo annual weigh-in
All creatures great and small are weighed, including this katydid (Yui Mok/PA)

Animals at London Zoo are regularly weighed and measured to monitor health, development and identify pregnancies.

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

ZSL London Zoo annual weigh-in
Kiwi, a capybara, is lured onto scales with yummy treats (Yui Mok/PA)

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.”

ZSL London Zoo annual weigh-in
A Vietnamese magnolia snail is among every mammal, bird, reptile, fish, and invertebrate across the zoo to be weighed and measured (Yui Mok/PA)

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

The zoo opened in 1828.

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