The Lesser Blackbacked Seadragon was a dragon species from the book series first mentioned in How to Speak Dragonese.
Appearences
They are first mentioned in How to Speak Dragonese. Gobber the Belch gives a class to the vikings in training about how to raid a peaceable fishing boat in the middle of a fog. Since the fog is so thick that the fishermen won't see the viking coming, then the vikings won't see the fishing boats either. So in order to find a ship the vikings were supposed to follow the racket produced by flocks of this dragon, as they followed fishing ships hoping to get a bite.