SHARKS ANJ) SKATES. 



SHARKS AND SKATES. 



The sharks, at least by reputation, are known to all. Their name has 

 been taken as a synonym for rapacity and cruelty, and their chara< 

 warrants it. They are admirably adapted for a predatory life. The} 

 provided with an awful array of teeth, and the arrangement of th uld 



not be bettered. They are placed on the jaws, row behind row. and each 

 tooth is triangular, and is itself minutely toothed on its edges. One i 

 is in active use at a time, while the others, inside the mouth, point l»a<k- 

 wards or down the throat, and these are effective in preventing the escape 

 of any prey after once it has obtained entrance to the mouth. Then thi 

 is but one way in which it can go — towards the capacious guild. When 

 the teeth of one row fall out or are lost by any injury, those of the d 

 succeeding row move up to take their place. 



The sharks are strong swimmers, and their bodies are capable of bend- 

 ing to an enormous degree. They have no true bones, the whole skeleton 

 being cartilaginous, thus admitting of great flexibility. The tail is not like 

 that of ordinary fishes, but is composed of two unequal lobes, the backbone 

 being continued into the upper and larger lobe, a feature paralleled else- 

 where only among the sturgeons and gar-pikes. On the back is a stn 

 dorsal fin, which frequently shows above the surface of the water and gives 

 the bather or sailor warning that one of these monsters is at hand. 



Sharks breathe by means of gills; they take water into the mouth 

 (which is situated on the under side of the head), and pas- it back and out 

 through gill-clefts on the sides of the neck, where the fine filamentary gills 

 extract the oxygen from it. In ordinary fishes there is but on.- externa] 

 aperture for the escape of the water after it has passed the gills, hut in the 

 sharks each gill-cleft (there are usually five) has its own aperture on the 

 side of the neck, as may be seen in all of our figures. In their digestive 

 apparatus they have a peculiar structure for increasing the surface, ; 

 thus affording more facilities for assimilation. In the intestine, folds - 

 inward from the wall, and these are coiled in a spiral, which may either 1 

 like a screw or more after the fashion of a very wide watch-spring. 



The economic importance of the sharks is very slight. Th< ir tie- 1 - 

 but slight value as food, but still in certain places the fishing for this pi 

 pose is carried on to a considerable extent. On this point Di 

 says : " In China and Japan, and many other eastern countries, th 

 kinds of sharks are eaten. Sharks' fins form in India and Chin 

 important article of trade, the Chinese preparing from them 

 using the better sorts for culinary purposes. The fins are obtt 



