THE MAMMALS 



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like to go down a freshly planted garden furrow because the burrowing 

 is easier there ; the fact that they uproot the plants growing there is only 

 incidental. They have powerful front legs with sharp claws, and they 

 move along underground with the same movements that a person uses to 

 swim the breast stroke under water. Their eyes have become degenerate 

 and the eyelids remain fused together throughout life. The external 

 ears also are covered with skin. Both of these adaptations have per- 

 sisted because they have survival value — they keep dirt out of these 

 organs. 



The shrew is an animal which has been described as the fiercest 

 animal in existence, ounce for ounce. Shakespeare showed that he knew 

 his biology when he selected the title, "The Taming of the Shrew," 



Photo by Winchester 



Fig. 28.7. A mole. These highly specialized mammals spend most of their lives under- 

 ground. Their front legs are developed for digging and the eyes and ears have no 

 external openings so they will not get dirt in them. 



for his clever comedy. The shrew is the smallest of the mammals and 

 is about as small as any warm-blooded animal can be. The smaller the 

 mammal, the greater is the exposed body surface in proportion to its 

 size and the more it has to eat to keep warm. When a tiny shrew is 

 placed in a cage with a mouse which is many times larger, the mouse 

 will be so terrified that it will allow the shrew to eat it with hardly 

 a token resistance. A shrew must eat about one and one-half times its 

 body weight per day in order to live. Think of a person eating 225 

 pounds of food per day and you can appreciate the problems facing 

 the shrews in finding and digesting sufficient food to keep alive. A 

 shrew will die of starvation in a few hours if it is deprived of food. 



