User blog comment:WikiBuilder1147/Classification of species/@comment-1743498-20130212212521

Taxonomy systems unique to certain planets isn't out of the question, but a universal one would be massively beyond reason. The main reason is that species on different planets lack a recent common ancestor other than perhaps microbes that came from similar asteroids.

Even creatures that just look similar can be radically different in terms of genetics. For example, the tuatara looks a lot like a lizard, but is actually a closer relative to dinosaurs that lived 200 million years ago. Not to mention that it has a third eye unlike almost any other vertebrate on Earth.

I think it would be far more accurate to describe a creature for what it is rather than trying to compare it to others. Everything about the creature should be able to be summed up in the infobox: type, symmetry and diet. With type being a generic classification based on what Earth creature it resembles the most.