SLICKING FOR FLYINGFISHES 



The skippers are more closely related to the fly- 

 ingfish, and when hard pressed by bonitos or other 

 enemies they leap out and flick themselves along 

 above the surface by vibrations of the tail until they 

 seem almost to be fully sustained by the air. Thou- 

 sands of skippers thus jump out at once, presenting 

 a most remarkable appearance. This method is ex- 

 actly that of an aquaplane, shooting along obliquely 

 by the thrust of the propeller. The nearest approach 

 to flying is shown by Euleptorhamphus and the un- 

 related fresh-water flyingfish of South America. 

 The latter skitter along, their sharp keel-like bodies 

 trailing and leaving a narrow wake, while the former 

 actually get up above the surface. From the point of 

 view of comparative movement and emersion, these 

 various examples are of interest, but they are end 

 products and in no way explain the actual evolution 

 of the real flyingfish. Fossil flyingfish are almost 

 unknown, and only theoretically can we reconstruct 

 the development through the ages from fin to wing. 



The question of true flight versus gliding has 

 been argued for a generation and has been settled 

 conclusively. The flight of these fish is exactly like 

 that of the gliders of human manufacture, where 

 the impetus is given by a great elastic cord and the 

 consequent progress and suspension are shared by 

 the impetus and the upward pressure of the air. 

 In the case of the man-made affair the impetus 

 soon gives place to utihzation of air currents, rising 

 upward from valleys and slopes, while with the 

 fish the impetus probably accounts for four-fifths 



73 



