196 ] Snakes and Frogs and Their Relatives 



snake's unblinking stare, caused by its lack of movable eyelids, 

 gives us the idea that it is trying to hypnotize its victim. 



6. False: Snakes spring from the ground to attack a victim. 

 True: No snake jumps clear of the ground to strike. 



7. False: Snakes are slimy. True: Snakes are completely covered 

 with dry scales. 



8. False: Snakes have yellow blood or no blood at all. True: 

 Their blood is red and practically the same as that of a mammal. 



When you get to know the truth about snakes, and understand 

 why they behave as they do, you may find yourself regarding them 

 with interest rather than horror. 



Reptiles Past and Present 



Snakes are reptiles, a name scientists have given to a group of 

 animals that includes lizards, turtles, crocodiles, and alligators. 

 The name was suggested by the Latin word for "creeping." 



Reptiles were the most important animals on earth millions of 

 years ago. Porpoise-like species lived in the ocean while batlike 

 reptiles flew in the air. The land was dominated by reptiles called 

 dinosaurs. At first they were no larger than rabbits; later they 

 developed species far bigger and heavier than the largest elephant. 

 We do not know for certain why these mighty creatures dis- 

 appearedchanges in the earth's climate may have been the cause. 

 Whatever the reason, the importance of reptiles dwindled and 

 warm-blooded mammals became the outstanding animals. 



THE COLD-BLOODED SNAKES 



All reptiles are alike in being covered with scales or bony 

 plates, and all are cold-blooded. (They derive their heat from 

 external sources, whereas warm-blooded animals derive theirs 

 from within their bodies.) We find, however, that reptiles vary 

 greatly in the way they live and in the places they inhabit. Many 

 of them dwell only in regions where summer conditions prevail 

 all year; but there are some snakes that have to adjust to a climate 

 with extreme variations of heat and cold. 



Sleeping Through the Winter: Though cold does not endanger a 

 snake's life until it reaches a few degrees below freezing, a lesser 





