User blog comment:Jrooksjr/Category and Sub-Category for Animal pages/@comment-4175522-20121212001943/@comment-409884-20121212151620

So you would prefer options 2 or 3

I did not mention this in the main part but the sub-categories no matter which option is preferred would be listed in their upper-category even if the images are not displayed in the upper-category

Category:Chinchilla would be a sub-category of Category:Porcupine, Category:Porcupine would be a sub-category of Category:Rodent and of course Category:Rodent would be a sub-category of Animal and so forth.