Here is an opinion piece about zoos. It is well structured and contains interesting vocabulary. It may be useful for my NI2 students of English.
The human being´s superiority to animals means that we have always tended to treat them badly. Many are used to work, others to earn money for us, others to research consumer products. In my opinion, keeping animals in zoos is generally just another example of this cruel treatment.
Firstly, many zoos are old and dirty and the animals are kept in miserable conditions. Often the cages are so small that the animals suffer psychologically, for example the polar bear, which eventually goes mad in captivity
Secondly, the animals often live in a climate which is not natural to them. This means that elephants may have to tolerate cold and rain, or penguins heatwaves.
On the other hand, it is true that a few good zoos play an important role in the conservation of species. However, these are a minority, and in any case this job is better done in protected areas in the countries where the animals usually live.
In conclusion, I think that most zoos should be closed down, an animals should only be kept in captivity in conservation areas where they live in the natural environment. And if people really want to see animals from far-away countries, they should watch the wildlife documentaries on TV.