DIFFERENT WAYS OF SWIMMING 



the strength of "wing" it possesses, has its own 

 length and kind of flight. Some are more favoured 

 than others; and the most active, the best equipped 

 among them, are the eagle rays. 



They have an extraordinary appearance, even for a 

 skate-like fish. Their snub-nosed head, with large 

 eyes and the muzzle of a batrachian, attracts attention 

 by its unusual form. The wing-shaped fins strike 

 one by their extent and contour lines. Very full, with 

 a spread almost twice the length of the trunk, they 

 stretch backwards and end in a point like the wings of 

 a swift-flying bird, justifying the names " sea eagles " 

 or " sea hawks " by which they are sometimes called. 

 But these names are only half deserved. If the re- 

 semblance of the wings is responsible for their adoption, 

 there is absolutely no resemblance to the bird as regards 

 the beak. The eagle rays have a slit-shaped mouth, 

 with large flat teeth, set close together like paving 

 stones, and capable of crushing hard objects. They 

 are incapable of seizing living prey which can defend 

 itself or get away. Beasts of prey, eaters of flesh they 

 certainly are; but to the detriment of the shell-fish 

 which lie on the bottom, whose calcareous envelope 

 they crush with their jaws, to find inside the nourish- 

 ment they seek. For this reason they are feared by 

 oyster-farmers, who regard them as dangerous enemies 

 against whom measures must be taken, for they 

 penetrate the oyster beds and destroy the oysters which 

 are placed there. 



The skates and the eagle rays are not the only fish 

 which are able to use their pectoral fins to move and 

 swim as the birds fly. The gurnards do the same, 

 although in a different way. When I was dealing with 

 fish that walk, I referred to the strange appearance of 

 these creatures, which rest on finger-like parts of the 

 pectoral fin, and even walk along the bottom with their 

 help. But they also swim, and for this purpose use the 

 remaining part of the fins which are spread like broad 

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