Keeper Luke Harding poses with a Jackson's chameleon during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

A zoo worker counts Humboldt penguins during a photocall at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Keeper Veronica Heldt poses with meerkats during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Keeper Jamie Mitchell poses with a Mexican red-kneed tarantula during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Keeper Jessica Jones poses with a llama during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Keeper Janet Abreu counts Humboldt penguins during a photocall at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Keeper Collette Gibbings look at a tank full of moon jellyfish during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Humboldt penguins swim in their pool during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

A llama looks at a photographers lens during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Keeper Luke Harding poses with a Jackson's chameleon during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth 

Children look at Humboldt penguins swim in their pool during the stock take at London Zoo in London, Britain January 4, 2016. REUTERS/Stefan Wermuth