I don't think any animal is essential for a zoos. TP Berlin does just fine without any great apes, Nuremberg, Frankfurt, Plzen and others are doing fine without Elephants. Prague is fine without hippo, Zurich fine without Giraffe and Ostrava more than fine without Rhino.
The only thing a zoo really needs is to be different in a way compared to the local competition and the collection doesn't really matter then, though some charismatic species that have wider appeal should be present. Which species those are isn't really important, except from a theming point of view... A zoo like Bern works just fine with mostly European species and doesn't need exotic megafauna, but to be an interesting zoo for the public they do need some charismatic species, which are Bear, Wolf, Wisent, Leopard, Puffin and Seal in their case.
A good zoo can create lasting memories from a good enclosure with crabs or dung beetles. Thus without spending millions on pandas, that are frankly less unique than a good invertebrate enclosure....
The only thing a zoo really needs is to be different in a way compared to the local competition and the collection doesn't really matter then, though some charismatic species that have wider appeal should be present. Which species those are isn't really important, except from a theming point of view... A zoo like Bern works just fine with mostly European species and doesn't need exotic megafauna, but to be an interesting zoo for the public they do need some charismatic species, which are Bear, Wolf, Wisent, Leopard, Puffin and Seal in their case.
A good zoo can create lasting memories from a good enclosure with crabs or dung beetles. Thus without spending millions on pandas, that are frankly less unique than a good invertebrate enclosure....