What separates animals into different Phylums?

Question

What separates animals into different Phylums?

Answer 1

There are 9 layers of scientific classification and phylum is fourth down I think.  Example is that humans are in the animal kingdom, phylum chordata (vertebrate, we have a spinal chord and internal skeleton instead of an exoskeleton), class mammalia (as opposed to avian, birds), order omnivora (we eat everything).

Then the phylum would be seperated into I believe body structure, internal skeleton vs exoskeleton vs no skeleton, etc.

Answer 2

taxonomy and taxonomists

Answer 3

After kingdom comes phylum. Animals in the same phylum have the same kingdom. When animals in a kingdom slightly differ, they go into separate phylums.