Look great Adriana :D. Just some advice which might help to develop your creatures. Think about where they live and whether or not they are hunters or if they are prey. That way features etc will be easier to place :).
Maybe also mix up a few other radically different elements to - perhaps some lionfish-type spines, or maybe look to the marine dinosaurs?
I already have looked at dinosaurs and lionfish. I am trying to puick a bit of everything really :P