DIFFERENT WAYS OF SWIMMING 



sharply to one side, go up or down with an easiness, 

 a flexibility, a continuity which nothing interrupts or 

 alters. They even stop and remain stationary, still 

 making use of their two pectorals, the action of which 

 is slowed up for this purpose. But if a sudden burst 

 of speed is required, then, as in the case of the great 

 swimmers, the caudal fin comes into vigorous action; 

 it acts like a scull, and pushes the body forward with 

 a speed the pectorals alone could never give. All the 

 deep-sea fishes are able to make use of this dual system 

 of swimming. It is that employed by the tunny, 

 and other related strong swimmers, and is characterized 

 by the frequent predominance of the action of the 

 caudal scull, and the less general use of the pectoral 

 oars. 



The fishes of the second category are more varied. 

 If, when in a state of repose, they seem very much 

 alike, all spread out on the bottom in attitudes deter- 

 mined by their particular shape, they differ and can 

 be distinguished from one another as soon as they 

 rise to swim. It is particularly in them that we can 

 observe dissimilar methods of swimming. Their 

 diversity of action in this respect is one of the most 

 interesting features of life in the aquarium. 



Among the most remarkable are the skate, the eagle 

 rays, and the electric rays or torpedo fish. We see 

 them lying on the bottom, their wide bodies outspread, 

 looking more or less as they look on the fishmonger's 

 slab before being cut up for sale. The only sign of 

 life is the movement of their bulging eyes, or that of 

 the respiratory organs. We are surprised when they 

 move and get ready to swim. Then they rise and, 

 agitating the extended sides of their bodies, use them 

 to beat the water as a bird uses its wings to fly. There 

 is no better word than " flying " to denote their manner 

 of swimming. But how much more flexible and 

 elegant is their swimming than the flight of a bird! 

 In the bird the wing is a dry, hard limb, covered with 



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