THE STRUGGLE FOR FOOD ^ND ROOM 279 



swiftly; the catfishes stiffen a long spine in each pectoral 

 fin, which makes a bad wound ; the so-called poison-fishes 

 of the ocean have spines provided with poison glands ; the 

 sting-rays, common on the coast, have a strong, jagged 

 spine in the tail, armed with broad saw-like teeth, which 

 inflicts a bad, ragged cut. The torpedoes or electric 

 rays found on the sandy shores of all warm seas have on 

 each side of the head a large honeycomb-like structure 

 which gives a strong electric shock whenever the live fish 

 is touched. Among the reptiles of our country the poi- 

 sonous bite of the rattlesnake, copperhead, and water- 

 moccasin is a familiar example of a very effective special 

 means of defense. 



Certain special habits of animals, too, help much to 

 protect them, and to save their lives. The migration of 

 birds takes many from a bleak, foodless winter to the 

 luxuriant tropical forests, where there is plenty of food 

 and the weather is mild. The hibernation or "winter 

 sleep " of bears, snakes, and lizards carries them safel}- 

 through a season when food is scarce or wanting alto- 

 gether. And some animals come from their holes and 

 hiding-places to hunt food only at night, when most of 

 their enemies are asleep. 



Finally (as we shall learn particularly in the next 

 chapter), many animals are colored and marked in such 

 manner that they match or fit in so well with the soil or 

 leaves or stones on which they rest as to be indistinguish- 

 able. And this scheme of harmonious coloration is one 

 of the most successful and wide-spread of all the special 

 protective devices. 



Examples to be looked for by the pupils. — Only a 

 few of the special means for food-getting and protection 

 are mentioned in this chapter, and those animals which 

 may be most readily observed by the pupils have pur- 

 posely not been referred to. When we come upon such 



