78 A HISTORY OF FISHES 



and use these to make the flights through the air for which 

 they are famed. In order properly to understand these flights, 

 it is necessary to look at some more generaHsed members of the 

 same order, the Skippers {Scombresox) , Gar-fishes {Belone), and 

 Half-beaks {Hemirhamphus). These fishes, especially the Half- 

 beaks, are experts at leaping or "skittering" over the surface 

 of the sea, but the pectoral fins, being comparatively small, are 

 only able to raise the head and forepart of the body out of the 

 water, the tail remaining submerged and vibrating rapidly. 

 There can be Httle doubt that the prolonged aerial excursions 

 of the Flying-fishes are improvements upon the spasmodic 

 jumps of the Gar-fishes and their allies. They are undertaken 

 primarily in order to escape from enemies, or when the fishes 

 are alarmed by approaching ships, but sometimes without any 

 apparent cause. The actual flight seems to be carried out as 

 follows: the fish accelerates its speed, rushing along near the 

 surface of the water with its tail moving very rapidly from side 

 to side; it then makes a sudden leap out of the sea and is borne 

 along through the air with the pectoral fins outstretched and 

 practically motionless. The chief motive power of this soaring 

 flight is supphed by the tail, there being Httle, if any, actual 

 flapping of the "wings" as in birds or bats; the pectoral fins 

 act merely as parachutes which enable the fish to glide through 

 the air. ^ The flight appears to be checked by movements of 

 the pelvic fins, which are often enlarged, and the fish returns 

 to the water tail first, although, according to Dr. Hankin, in 

 one species "they plunge head foremost into the water without 

 any visible attempt to check their speed." He estimates the 

 longer flights as from 200 to 400 metres in length, and the 

 average speed under favourable conditions as from 10 to 20 

 metres a second. The fish seems to be quite incapable of 

 steering itself in the air, but during the flight the hinder part 

 of the body may become re-immicrsed in the water, and by a 

 vigorous flip of the tail the fish changes its direction to the 

 right or left and, at the same time, gams increased speed. As 

 a rule the flights are close to the surface of the sea, but the 

 fishes are not infrequently carried upwards to a height of 

 15 or 20 feet by a current of air, and iii this way often land on 

 the decks of ships in stormy weather. In the Flying Gurnards 

 [Dactylopteridae) the pectoral fins are even more enlarged, but 

 here they seem to be actually vibrated during flight, moving up 

 and down Hke the wings of a butterfly. These flights, however, 

 are more clumsy and less successful than those of the true 



