London Zoo begins its annual animal weigh-in

Zookeepers armed with clipboards and calculators roamed the nearly 200-year-old zoo, tallying weight, height and size of animals.

According to Angela Ryan, the Zoo's animal operations manager, the information gathered will be shared with other zoos and conservation bodies globally.

With at least 20,000 animals calling the zoo home, keepers will spend the rest of week to complete the weigh-in