The dragons known to the Hairy Hooligan Tribe are grouped into one of seven "classes" based on their similar abilities or features that they posses (unlike modern taxonomy which is based on shared physical characteristics). Dragons can also be moved to another class if new discoveries are made that would better fit the dragon in another class. The seven classes are Stoker, Boulder, Tracker, Sharp, Tidal, Mystery, and Strike. As mentioned in the exclusive short, Book of Dragons, and in We Are Family Part 2, Gobber's great-great-great grandfather Bork the Bold was the first to categorize dragons into different classes.