Increadible piece! Is this monster perhaps based on the Terrible Shark/Dogfish(or The Whale Monstro, from the Disney adaptation), from Pinocchio? Aside from the Biblical beast of te same name, of course.
I love how you handled the body, it looks like it could go on forever, due to the perspective and the murkiness around the sides and edges.
Only thing that I think is missing are some noticeable scars, this thing should looks like it's been around a while, and it's had a lot of fights. It would also allude to there being other things in the deep that are possibly just as big or bad, if not more.
This is awesome work though, I love a good sea monster, they are about the only kinds of monsters that still scare me.
I just wanted to let you know that I have been seeing this image used for advertisements all over the internet I'm not sure which company is doing it because its always in the side bar advertizements and it does not always show up when I click on it. I will send you a screen cap showing it though. Here is the screen cap: [link]
and here is the url of the page I found it on. It's constantly changing and cycling through images though so I'm not sure if it will still be there or not (if you reload the page a few times its bound to surface again)... [link]