OMG that made me laugh. That doesn't really look like a swimming sharptooth though. It looks like whatever Mo is. Sharks don't have 4 fin thingy's.
Mo is likely a predator. I don't know of any sea reptile (referring to the dinosaur-like ones) that were herbivorous.
And brek had specified that Ducky's sharptooth form was the same as Mo's species. I didn't choose the form. If it were up to me, I likely would have made Ducky a bellydragger like Spike is or perhaps a plesiosaur like Elsie was.