As far as intellectually stimulating, this picture has a fairly simple concept: Larger fish eating an already large fish. Where this picture may be causing you grief: The subject is smack dab in the middle, and it's side profile. Is this a bad thing? Well, yes and no. You've managed to pull off an interesting picture with these inherantly bad stigmas: even though it's side/center, it's still a fun image. I think you could push your values farther, introduce a bit more blue to the shadows, try it from a different perspective, play up the danger angle more, there's infinite options for you.
This picture may be fighting on what it's trying to illustrate: are we looking at the interaction of the whale being eaten by the fish creature? Or are we looking at the design of your creature and how it relates in comparison to size of other animals? I in no way think it's a bad image, i just believe it could be pushed a LOT farther.