The zoo grows and prospers: new animals are added regularly and the animals provide offspring from time to time. Once a zoo is full and few new animals are added, it can become boring and customers want something new.
Also, zoo managers find it useful to share their animals by sending them to other zoos. Of course, the new zoos like the additions and reward those who sent them. Two extra delivery trucks are added for the game for two and bonus material is included for Aquaretto. This is just what is needed for those who cannot get enough Zooloretto.