At London Zoo, all creatures great and small are counted at the beginning of the year to make sure they know exactly how many residents there are!
This lot are squirrel monkeys - looks like they know how to smile for the camera!
This keeper is trying to count the snakes - imagine doing that with a Dumeril's boa wrapped around your shoulders!
Keepers are braving the cold to tot up more than 750 different species, including flamingos.
"We need to know not just how many animals we've got, but also who we've got," the zoological director David Field said.
The information will be used to help a worldwide conservation effort because some of the zoo's animals are critically endangered species.
Thanks to the famous adverts, meerkats like this one get more visitors every year!
This train millipede looks a little bit slimy... would you want to hold it?!
Workers at London Zoo reckon the count will take a whole week and that the population will be a little bit higher than the 16,000 recorded last year.