perhaps get rid of the black outline? Also, maybe lighten it up a little, the piece looks very dark and the colours are all kind of crammed into a very small space. Cool concept though, GO TURTLE DUDE!

 Hrm. Alright, yeah I'll try that, thanks t3nshi. I also just now notice that his arm gets a bit too wide, so I'll have to fix that too, Any other suggestions anyone?

Cool.

Eyes indicate much more rotation than does the snout, almost like the head is twisting back and forth.

The extreme poses don't look like the same creature as the middle pose. Smooth motion, though.

 you should make the upper part of his body go up and down a pixel in some frames and his left leg could go a little more forward :3