Every year London Zoo counts up how many animals it has living there, and Hayley went along to help out.
It's called a stock take and it's the same as a shop counting jumpers or books, except zoo keepers need to know how many animals it has.
Fish, insects and bugs are some of the hardest to count because they're really small, and they move around a lot.
At London Zoo there are more than 750 different species including gorillas, squirrel monkeys and tigers.
The job of counting the creatures is even trickier this year as the number of animals has risen over the last 12 months.
The zoo is home to new pair of nosey aardvarks, some prickly porcupines and the first lion cubs born at the zoo in over 10 years.