266 UNDERWATER GUIDE TO MARINE LIFE 



Plectognaths: Suborder Plectognathi {"jaws woven together") 



Here are united three rather distinct groups which have formerly been consid- 

 ered separate suborders: (1) the Sclerodermi ("hard skin") or triggerfishes and 

 filefishes, (2) the Ostracodermi ("box skin") or trunkfishes, and (3) the Gym- 

 nodontes ("naked tooth") or puffers and porcupine fishes. But because of the 

 common origin of these fishes from scaly-fin fishes and because of several trends 

 which these three groups show in common, the splitting of this group in three 

 parts may not be justified. All show a very reduced gill opening, a trend defi- 

 nitely present in some scaly-fin fishes, notably tangs. All reduce or lose the 

 ventral fins. All have lost typical scales, having plates or spines in their place. 

 All have several jaw bones fused, hence the term "Plectognathi." Many, espe- 

 cially the gymnodonts, develop poisonous alkaloids in their flesh or viscera. The 

 Polynesian maki-maki or deadly death, Tetraodon hispidus, has deadly flesh. 

 The flesh of porcupine fishes causes a nerve poisoning called "ciguatera." Some, 

 however, are good eating. Northern puffer tails are sold as "sea squab." The 

 plectognaths all have small mouths and are feeders on small invertebrates or 

 marine vegetation. 



TRIGGERFISHES: Family Balistidae 



The word "balistes" means "crossbow" and is applied to the triggerfishes 

 because of the very odd arrangement of the spiny dorsal fin. The large first 

 spine locks erect into place and can be released by depressing the third spine. 

 These compressed, deep-bodied fishes have hard scales imbedded in the skin 

 and no mucus and therefore feel decidedly leathery. The bones of the ventral 

 fins beneath the skin form an erectile flap which gives the bellv outline a very 

 odd shape, pointed and deep just ahead of the anal fin. The soft dorsal and anal 

 fins are much alike in size and shape and are used in propelling the animal. 

 They flap from side to side, both fins flapping first to one side then to the other. 

 This is especially noticeable in the ocean triggerfish, which keeps more to open 

 water than the others and also swims more constantly. These are primarily 

 tropical reef fishes of world-wide distribution. 



COMMON TRIGGERFISH (cucuYo) : Balistes caprJsens—Color Plate 9 



Size: Averages 10 inches. Up to 20 inches. 



Weight: Up to 4 pounds. 



Distribution: West Indies to Cape Hatteras. Strays to New York. Western 

 coast of Mexico. 



Identification: Dull brown with mottled sides when near cover such as sargasso. 

 Plain gray in open water. 



Habits: This fish is found either singly, in small pods, or swimming with other 

 small fishes such as grunts. It keeps to reefs, rocks, and hard bottoms, swims 

 actively, and feeds on worms, crustaceans, and molluscs primarily. The voung 

 keep to the shelter of sargasso weed or floating objects. 



QUEEN TRIGGERFISH (oLDWiFE, cociNo) : Balistes vettda—Color Plate 9 



Size: Averages 1 foot. Up to I'/z feet or more. 



Distribution: West Indies to Florida, stragplina to New York. 



