triggerfish (redirected from Trigger fish)

triggerfish, any of several species of tropical reef fishes with laterally compressed bodies, heavy scales, and tough skins. They are named for the mechanism of the three spines of the 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, the fish dives into the coral and erects the spine, releasing it only when the danger has passed. Triggerfishes have powerful, chisellike teeth adapted for cracking the coral and mollusks on which they feed. They average 1 lb (0.45 kg) in weight and 1 ft (30 cm) in length and are common around the West Indies and Florida. The common triggerfish is variably colored in mottled browns, yellows, or grays, and the queen triggerfish is strikingly colored in blue, green, and yellow. The ocean triggerfish is up to 2 ft (60 cm) long and weighs 3 to 5 lb (1.4–2.3 kg). Triggerfish are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Tetraodontiformes, family Balistidae.

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triggerfish

Triggerfish (Balistes conspicillus).

(credit: Douglas Faulkner)

Any of about 30 species (family Balistidae) of shallow-water marine fishes, found worldwide in tropical seas. Triggerfishes are deep-bodied, usually colourful fishes with large scales, high-set eyes, and three dorsal-fin spines, which they use for protection. When a triggerfish is threatened, it darts into a coral crevice and erects its large and strong first spine, which it locks in place with the second (the “trigger”); when the trigger is later withdrawn, the first snaps back down. Though generally considered edible, some cause food poisoning. The largest grow 2 ft (60 cm) long.