Ok so i've been searching in the internet for information on this topic and I have found Something that might be interesting.
This is a recap on information that can be found here http://www.mmocultur...#prettyphoto/7/ .
To save your time this is how it's going to look:
As there is no official number yet, but according to exclusive presentation slides, there are currently 8 different types of dragons. Each slide represents the dragon class:
1) Heavy (thick outer skin, able to carry heavy weights)
2) Predator (balance in both speed and attack)
3) Rush (fastest land travel speed, hunts in numbers)
4) Flying (rulers of the skies, the only dragon type with which can fly other than Ancients)
5) Gliding (gliding ability due to body structure, ambushes prey)
6) Aqua (strong jaws and moves fastest in the water)
7) Bug (a type with various alternative looks and abilities)
8) Ancients (rarest dragon type, able to fly)
You can catch them and train (as the presentation suggests). Keep in mind that Ancient dragons might (logically) be the end-game dragons, while the others can be caught early in the game.
P.S. Hope this helped!