Any of several species of tropical coral reef fishes in the order Tetraodontiformes, family Balistidae, with laterally compressed bodies, heavy scales, and tough skins. Triggerfishes are named for the mechanism of the three spines of their first dorsal fin. When the fish is alarmed the first of these spines is locked upright by the second and drops only when the latter is pressed like a trigger. The function of this reaction is to lock the fish firmly in a mass of coral when attacked. Triggerfishes have powerful, chisel-like teeth adapted for cracking the coral and mollusks upon which they feed.