I don't know how many times I've corrected people in forums who said that Eastern dragons are reptiles, have lizard scales, etc. and explained that they actually have fish scales and catfish whiskers. Now, I'm shocked that Kaido didn't eat the mythical model of the Ryu Ryu and it wouldn't surprise me that Oda just made the change for the sake of cheap subvertion as he likes, but this opens two exciting possibilities:
1) How is the actual mythical model of the Ryu Ryu family? Because right now I have no idea. I mean, Kaido's dragon is literally a ryu.
2) How are the common and ancient models of the Uo Uo family?
Regarding point 2, there's the possibility that it refers crustaceans, even though it may sound crazy. In the East there's a strong cultural connection between lobsters, crayfish, etc. and dragons, to the point that "uo" itself means lobster in some languages and, in Chinese at least, "lobster" is translated as "dragon shrimp". There also are many designs in popular works that combine dragons and crustaceans.
What do you guys think?