I think you did a great job with Jay's design. I've always found it terribly hard to anthropomorphise any animal that doesn't at least have legs, so I can really appreciate that you managed to pull it off with a shark!
I think my favourite part would have to be his tail, which is just so cool. Love his little ear-fins, too.
Seals and sea lions are among my favourite animals and I've tried to draw anthro versions of them before and failed quite miserably - but oh well, I'll figure it out someday!
His tail is definitely amazing. It makes me want to draw him just to be able to draw the tail. You know, I can kind of imagine him hanging out with my fursona Sym, who also loves the ocean. Perhaps I shall draw them together. I do need to draw more of Sym anyway . . . heck I need to draw more of anything, it's ages since I submitted something here!