[Munch's Master]

I don't think fuzzles are vertebrates or invertebrates, they seem compeletly different. I'd guess the following were vertebrates:
Gabbits,(Amphibious) Mudokons, Elums, Interns, Glukkons, Vykkers, Sligs, Steef, Outlaws, Wolvarks, Slogs, Slegs, Clakkerz, Chroniclers, Meeps, Stunkz, Chip-punks, Searexes (Aquatic)
And the invertebrates are:
Paramites, Slurgs, Fleeches, the variuous bugs and beetles that Stranger uses, Meetles, Mugs
And fuzzles fall into a category of their own. Scrabs and Meeches could be either, having seen pictures of them, although I'd imagine they'd both be vertebrates. No telling what the more obscure creatures that we've never properly seen are (eg. Guardians)