FAUNA OF THE ALEUTIAN ISLANDS AND ALASKA PENINSULA 279 



The sea otter is stockier than the land otter, Lutra canadenis, 

 and has acquired other special modifications. Its specialized food 

 habits (discussed later) do not call for great agility, and this 

 may be one reason for the development of a heavier, somewhat 

 less streamlined body than the ancestral form — if we may assume 

 the ancestral form to be similar to that of the present-day Lutra. 

 But the sea otter has become more aquatic than its ancestors, 

 with much less dependence on land, and it has developed seal-like 

 flippers on its hind feet. Its front feet, on the other hand, appear 

 to have responded to a specialized use in handling sea urchins 

 and hard shells of mollusks that make up its principal food. 

 The soles of the front feet have become very thick hard pads, 

 and the toes have more or less coalesced — judging by the speci- 

 men examined in detail (mentioned above) the toes are hardly 

 functional as separate digits. The claws have become very weak 

 and pale colored and are placed well up on the dorsal surface of 

 the toes. They probably have little use. The whole structure of 

 the front paw indicates that it is used largely for resisting abra- 

 sion from hard sea urchins and shells; it seems incapable of 

 manual dexterity. In fact, the animal seems incapable of hold- 

 ing anything in one "hand." Yet, I have watched sea otters 

 feeding and have seen them use one paw to toss away, with a 

 forward motion, an unwanted fragment of shell or other sub- 

 stance. Possibly it was only "pushed" away. (Karl W. Kenyon, 



Figure 42. — Sea otter. 



