Not a problem Thaago. That Arrow one also looks like a spade, or a at-rest moth... very interesting shape. I also notices some jaggieness on the outside edges that could use some anti-alias love (google spriting anti-alias on how to work with that, there are many ways to go about it).
As for the (what you called) spines, they are antennae, for which there will be glowing lights in game (not very easy to show here) Currently they are outside the hit box so I don't think they themselves will catch any fire. Though I haden't thought about how awkward those may look if the ship around it is damaged (or the whole ship is destroyed). I'll have to give it a test, thanks for pointing that out.
The Tackle is like a more B-A version of the Brawler. Other than the lighting things which you already pointed out, this sprite could also use some help on the outside edges with AA.
Brainstorm your faction some more and see what kind of ships you want to thrown in there.
Finally, keep it up, you are doing a great job and I for one am eager to see how you do with editing those sprites.