[Seargentbig]

I remember a similar topic to this, and I recall I soon posted a similar conclusion as Bullet Magnet came up with - you can't classify them in the same groups as actual animals. Though you could probably group them up, sometimes in animal-like clasifications. Let me see...

Mammal/Reptile like (Mainly speaking, vertebrates. Some might not have a backbone, as such, but still have endoskeletons from which to anchor muscles. The difference between mammals and reptiles on oddworld seems to be much more ambiguous than here. As a matter of fact, things that might be described as reptiles might just be hairless mammals. Who knows?)
Critters
Fuzzle
Chippunk
Ratz
Bats
Meep
Skunks
Boombats
Sleg
Slog
Large and Hairy
Steef
Outlaw
Wolvarks
Elum
Large and Hairless
Sligs(Other?)
Vykkers
Interns
Grubbs(Amphibian?)
Scrab
Paramite
Mudokon (Possibly more bird like. Possibly could even be mentioned in large, hairy mammals/reptiles, but they only have a small ammount of hair, I think they fit better in here.)

Bird like (Feathers, anyone?)
Mudokons (Large, hairless mammals?)
Birds(Obviously)
Clackerz

Insect like (An exoskeleton, possibly in addition to an endoskeleton. Being the reason a paramite isn't one.)
Bees
Bolamite
Thudslug
Stingbees
Zappflies
Mugs/Meetles
Fireflies
?Fleeches(Other?)

Amphibian like (Can breathe in air and water)
Gabbits
Grubbs(Possible a large, hairless mammal. But in this case, it may be pointed out that they can swim.)

Mollusc like (The only reason I have to show that these three are related I can't think where I picked up. If someone knows, I would apprectate confirmation. It is interesting to note that none of these have any shells. Endoskeletons or no skeletons. How messy.)
Glukkon
Gloktogi
Oktigi (Thanks, Xavier)
Slurgs (Kudos to Primus inter pares for suggesting this. Though it could also be in Other.)

Fish like (Breathe water. Endoskeletons)
Searex

Other (They just don't fit anywhere else, or at least not very well)
Fleeches(Insect?)
Slurgs(Mollusc?)
Sligs(Large, Hairless Mammal?)