CHARACTERISTICS OF MARINE FISHES 159 



thorax often more or less under the bases of the pectoral fins. Fins occupying such 

 a position are said to be "thoracic". However, in some spiny-rayed fishes the 

 ventral fins are attached well in front of the pectoral fins, that is under the head. 

 When they are so situated they are said to be "jugular". The blennies, toadfish, 

 stargazers, and several other groups belong to the jugular fishes. The ventral 

 fin in spiny-rayed fishes is usually composed of one spine and a few to several 

 soft rays, the most usual combination among our common food fishes being one 

 spine and five soft rays. The number sometimes is reduced, however, to 1 spine 

 and 1, 2, or 3 soft rays, as in the sticklebacks, blennies, and others. 



Regeneration of Fins. If the "limbs" or fins of fish are broken or bitten oflF, 

 they will generally regrow. The regenerated fins may be somewhat deformed, and 

 so can be distinguished from the normal ones. A remarkable case of regeneration 

 in a pipefish, Doryichthys lineatus, was observed by the writer. -This particular fish 

 had apparently lost part of its tail in addition to its caudal fin as it had fewer 

 caudal rings than normal. Yet, a somewhat dwarfed and twisted regrown fin was 

 present on the last caudal ring. 



Function of Fins. The powerful muscles in the tail of the fish cause the caudal 

 fin to be used as a paddle for propulsion. The other fins serve chiefly as balancing 

 organs. A remarkable departure from the usual function of the paired fins occurs 

 in the flying fishes; the pectoral fins and in some species both the pectoral and 

 ventral fins are used as organs of flight. However, the fins do not function as 



(Courtesy U. S. Fish and Wildlife Service) 



Fig. 10-15. The California flying fish (Exocoetus calif orniensis) . 



organs of propulsion like the wings of a bird; rather, they are used only for 

 soaring or gliding. In effect, the fish takes a powerful leap from the water, and 

 when once in the air the large fins spread widely, helping the fish to glide dis- 

 tances of 100 feet or more (Fig. 10-15). 



The Mouth. The shape, size, and position of the mouth vary greatly. The most 

 usual type is that possessed by the common Atlantic herring, Cliipea harengus, in 

 which it is of moderate size, slightly oblique, and nearly terminal. Varying from 

 slightly superior to slightly inferior, it occurs among many common food fishes, as, 

 for example, codfish, sea bass, mullets, mackerel, snappers, and many others. 



A wide departure from the usual type of mouth occurs in the barracudas, which 

 have very strong, greatly prolonged jaws and a large mouth, similar to the 



