Great work so far!
Now I have some tips that could help this painting work better when it is finished.

-First: I know there is a situation going on between this two characters, but it actually is a little hard to understand right from the beginning , Try to make it as obvious as you can (as your friends if they get what's going on, if they get it right immediately, then you are done with this step!)
-Second: You did a great job panting the mouth! unfortunately it is done in a different angle from the rest of the shark, make sure you double check this. This happens to me all the time, It happens to everyone. Analyze this for a couple of minutes and do some sketches until you get it right
-Third: Work a bit more your composition. This is one works, but it is not the best you can give, I can see this, You have a great talent and you should push it even more to get a composition that works better. do some research and figure out what you could fix about it.

But most important: you are doing a fantastic work by pushing yourself to do images you don't usually do. That's the way we all get more experience and knowledge from. Keep it up!

Little extra note :
By no means I'm trying to say something is wrong in this image... I understand it is a WIP, The only thing I suggest is that you spend some more time improving this 3 points before continuing. You are capable of doing this image work better!

Keep it up! this image has so much originality...
...and congrats on you gallery, it is pretty good!

PS: My rating is based on your work so far.