These crabs have a wicked defense boost move, but at level 20-25 in qufim you can't counter it with Dispel. I thought it was just something you had to hit through, but then I accidentally hit one with an acid bolt after it used the Defense Boost. The acid bolt completely removed the effect, and debuffed it about the normal -def amount for an acid bolt. So, in short, keep a stack of acid bolts on you to counter their def+ move if you have a x-bow and decent marksmanship. The ability to counter that move increases your party's efficiency an amazing amount.
Is there a difference between this mob I just linked, and the mob on this page? Looks like the same thing to me. Level range of the Clipper I linked falls within the level range of this clipper.
-EDIT-
Never mind, I didn't notice that the blue linked mobs were all aggro versions.