cute. i love how you have that shadow "seen through the slimily" in slime, bunny, valentine and chick". You could probably try to edit snake and bat for a similar effect.
The manta and the giraffe are the less slimy-esque of the group, imho. They're too close of real shapes, and look more like inflatable caoutchouc puppets rather than a slimy trying his best to mimmic something he's just seen.
Any plan to animate a "morph show" ?
(oh, and imho, that double-outline (white around black) doesn't pay credit to your art -- but that could be just me
)