Why these animals are classified as they are?

Please provide me with the list of animals you'd like me to classify. I need to know which animals you're referring to before I can explain their classification.

For example, you could say:

* "Why are cats classified as mammals?"

* "Why are sharks classified as fish?"

* "Why are birds classified as Aves?"

Once you give me the animals, I can explain the reasons behind their classification based on their shared characteristics and evolutionary relationships.