I’ve been working on one single zoo since the release date and so far it only contains 10 different habitats and 13 species. Because I’m going very slowly, I like to alternate habitat building with beautification and construction building for visitor, I’ve always been able to have vets researching on the animals for the “bonus research”. The thing is that nothing is ever unlocked...I don’t know if this is a bug or something that still has to be implemented or is just not working for me.