Triggerfish range in size from 7.9 to 20 inches.  Triggerfish have an oval shaped, highly compressed body with a large head terminating in a small but strong- jawed mouth with teeth adapted for crushing shells.  The eyes are small, set far back from the mouth, at the top of the head.  The anterior dorsal fin is a set of three spines, and the first spine is stout and the longest.  All three are normally retracted into a groove.  As protection against predators, triggerfish can erect the first two dorsal spines: The anterior spine is locked in place by the erection of the short second spine, and can be unlocked only by depressing the second, “trigger” spine, hence the family name “triggerfish”.  With the exception of a few species, the genders of all species in this family are similar in appearance.