Nice entry. Here are my tips:
1.The creature should have a blue-ish overlay in order to look like it's in water, i would even lower the opacity to 90-95.
2. the lower part of the mouth doesn't look 3d (perspective is off). try to add the other layer of teeth behind and something like a tongue between them.
3. The are 2 types of bubbles : soap ones & water ones. You need the second type that looks like this:
http://www.pixshock.net/pic_b/31f006131aa76bed5f1dec01cc6d4203.jpg
You see,they are not round, cause water is heavy and makes them squashed. I think you can fix this from jitter.

Hello greymval, I really apreciate your comments and your tips, this is the way a criticism must be done

I fixed the things you help me to see.

For the bubbles, I used liquify

Thank you!

That's pretty scary! Really stunning details.

this is awesome

Thanks for the nice comments.

Great job man, now it's a kick-a$$ entry.

Yep, really nice now. GL!

Nice surprise!

Nice entry, well done

Amazing creature,great perspective,fantastic work...well done author

Very nice and cool focus here.

good work...

Thank you , I apreciate all your comments, votes and critiques.

Creepy ... very creepy. Sorry I missed photoing on this contest ... it would have been fun but hard, there is some really stunning work here ... this included! Bravo!