Ok i'll work on it but i'm gonna start a comic my first one is on the thread non and oddworld sprites can be posted here. Now time to work on that tail fin movment!
EDIT: Sorry for empty space on the movement sprite sheet
Speaking as an intermediate artist, you really ought to cut down on the size of that Sea Rex thingy. It wouldn't be terribly useful in games due to it's size, and only it'd be a boss. Since it seems more of a common enemy, you ought to shrink it and work more on it's shading and possible anatomy.