ADAPTATIONS 



335 



the stinging tentacles of the Portuguese man-of-war or under 

 ordinary jellyfishes. 



Some fishes called the flying fishes sail through the air with 

 a grasshopperlike motion that closely imitates true flight. 

 The long pectoral fins, winglike in form, cannot, however, be 

 flapped by the fish, the muscles serving only to expand or fold 

 them. These fishes live in the open sea or open channels, 

 swimming in large schools. The small species fly for a few 



FIG. 196. Flying fishes: The upper one, a species of Cypselurus; the lower, of 

 Exocaetus. These fishes escape from their enemies by leaping into the air 

 and sailing or "flying" long distances. 



feet only, the large ones for more than an eighth of a mile. 

 These may rise five to twenty feet above the water. 



The flight of one of the largest flying fishes (Cypselurus cali- 

 jornicus) has been carefully studied by Dr. Charles H. Gilbert 

 and the senior author. The movements of the fish in the water 

 are extremely rapid. The sole motive power is the action 

 under the water of the strong tail. No force can be acquired 

 while the fish is in the air. On rising from the water the move- 

 ments of the tail are continuous until the whole body is out of 

 the water. When the tail is in motion the pectorals seem in 

 a state of rapid vibration. This is not produced by muscular 

 action on the fins themselves. It is the body of the fish which 

 vibrates, the pectorals projecting farthest having the greatest 

 amplitude of movement. While the tail is in the water the 



