Titan triggerfish (Malcome Browne / CC BY)
Triggerfish (Balistidae) have compressed bodies and small eyes that are set far back from the terminal mouth. A unique feature of this family are their two-part dorsal fin spines. The first spine is stout and erectable. The second spine locks the erected first spine and allows the fish to wedge itself inside a crevice if threatened by a predator. Triggerfish can reach 75 centimeters (29.5 inches, titan triggerfish) in length. Triggerfish will attack divers who approach their nesting areas. The strong teeth of larger triggerfish species can inflict serious wounds.