MASTERS OF THE WATER-BONY FISHES 215 



Identification: This fish is characterized by wide, dark, vertical crossbands. 

 The spiny dorsal is A'ery reduced. The anal fin is much shorter than the soft 

 dorsal. 



Hahits: This is the fish that is commonly seen following sharks and vessels 

 at sea. It does not lead sharks to food but probably only hangs around them 

 for the scraps of the table. It is too fast and agile for the sharks to catch. The 

 eggs are laid at sea in the summer. 



Siviilar Species: The banded rudderfish, Seriola zonata, is banded while young 

 and replaces the pilot fish in following sharks and vessels inshore. It has a small 

 spinous dorsal as do other members of the genus Seriola. 



ROUND scad: DecaiHerns fiinctatus 



Size: Up to 1 foot. 



Distrihution: Cape Cod to Brazil. 



Identification: The body shape is slim and round like that of a mackerel. The 

 posterior lateral line is well armed with bony scutes in this genus. The dorsal 

 and anal fins are followed by a finlet in the true scads and the soft dorsal and 

 anal are of similar length. 



Hahits: The several species of small scads school in- and off-shore. They feed 

 mostly on small invertebrates. These are among the smallest fishes of this family. 



Similar Sj^ecies: The Pacific counterpart of the scads is the saurel (rough 

 scad or California horse mackerel), Trachurus symnietricus. Its entire lateral line 

 is armed with large scutes from head to tail, this being the only jack to show 

 such a feature. Otherwise it is like a typical scad, although of somewhat stouter 

 shape. It reaches 2 feet but is mostly much smaller. The range is from San 

 Francisco southward through the tropics. 



There is an Atlantic representative of the rough scad, and there are also several 

 species of Decapterus on the Atlantic and Pacific Coasts, which are difficult 

 to separate from the member of that genus already described. The goggle-eyed 

 scad or big-eyed scad, Trachnrops cnimenopthalmns, is much like Decapterus 

 species, but it has a huge eye and a slightly stouter shape (like the rough scad). 

 It grows to 2 feet and is found on both coasts north to Cape Cod and Cape 

 San Lucas. 



JACK CREVALLE (coMMON jack) : Curunx hippos—Color Plate 2 



Size: Up to 2!/2 feet or larger. 



Weight: Averages 2 to 5 pounds. Up to 20 pounds or more. 



Distrihution: Cape Cod to Brazil. Chiefly West Indies in the Atlantic. In the 

 Pacific, from Gulf of California southward. 



Identification: With this fish and others of this genus there is a very definite 

 tendency toward (1) the development of the high forehead and back, (2) 

 decurved lateral line armed posteriorly with bonv scutes, (3) deep, compressed 

 body, and (4) soft dorsal and anal fins of very similar size and shape— features 

 that we think of as being typicallv jacklike. The species are manv and 

 extremely difficult to identify. This species has a particularlv blunt forehead 

 and also possesses a dark spot on the rear edge of the operculum. 



Hahits: This fish is characteristic of inshore and offshore waters, chiefly 

 around coral areas. When young, this fish and others of its genus school. As an 

 adult, it is mostly seen in small pods. It is largely a surface predator on fishes. 



