300 



ANIMAL STUDIES 



gulps air until its capacious stomach is filled, and then 

 floats belly upward on the surface. It is thus protected 

 from other fishes, though easily taken by man. The torpe- 

 do, electric eel, electric cat-fish, and star-gazer, surprise and 



stagger their captors by 

 means of electric shocks. 

 In the torpedo or electric 

 ray (Fig. 171), found on 

 the sandy shores of all 

 warm seas, on either side 

 of the head is a large 

 honeycomb-like structure 

 which yields a strong 

 electric shock whenever 

 the live fish is touched. 

 This shock is felt severe- 

 ly if the fish be stabbed 

 with a knife or metallic 

 spear. The electric eel 

 of the rivers of Para- 

 guay and southern Bra- 

 zil is said to give severe 

 shocks to herds of wild 

 horses driven through 

 the streams, and similar 

 accounts are given of the 

 electric cat-fish of the 

 Nile. 



Among the insects, 

 the possession of stings 

 is not uncommon. The 

 wasps and bees are fa- 

 miliar examples of stinging insects, but many other kinds, 

 less familiar, are similarly protected. All insects have 

 their bodies covered with a coat of armor, composed of a 

 horny substance called chitin. In some cases this chitin- 



FIG. 170. Porcupine-fish (Diodon hystrix), the 

 lower ones swimming normally, the upper 

 one floating belly upward, with inflated 

 stomach. Drawn from specimens from the 

 Florida Keys. 



