Sea dragons are an evolved version of dragons. Much like their ancestors, they have all the qualities of being a dragon; scales, the classic four limbs, draconian features. But these guys do not possess wings or the ability to breathe fire. Instead, they can shoot water at high pressure to stun prey - which consists mostly of fish, octopus, shellfish and crustaceans. Their wings have evolved into fins and aid with turning.
They are small compared to their dragon counterparts, however some have grown to be as big, if not bigger, than blue whales.
They can breathe both air and water, so have no trouble if they have to move across land. Some have been known to travel long distances across land to reach lakes, where they lay their eggs in safety away from anything that could eat them.