THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 83 



Figure 44. — After hauling out, the otter usually rests on its back while 

 grooming and drying its fur before sleeping. (KWK 57-32-4) 



tration, as when an otter has been robbed of its food by another 

 otter. Perhaps the pounding of a hard-shelled mollusk against 

 another originated because of frustration when the otter could 

 not break, with its teeth, the shell of a food organism. At Amchitka, 

 where the shells of mussels are crushed by the post-canine teeth, 

 food pounding behavior is not observed. Where feeding was ob- 

 served in Alaska, hard-shelled clams were not eaten and mussels 

 (Mytilus) do not grow as large as those in California where they 

 are commonly pounded against a hard object (Hall and Schaller, 

 1964). 



When captive otters from Amchitka were presented with clams 

 that could not be broken with the teeth or crushed between the 

 paws, they broke them against a rock or another clam on the chest 

 (fig. 45) or by pounding them on the cement edge of the pool 

 (fig. 59). A female also pounded smelts (Osmeridae), and herring 

 (Clupeidae) which she did not particularly relish (fig. 46), and 

 she pounded a rock on the edge of her pool. Thus, animals that 

 came from an area where food organisms were not observed to 

 be broken by pounding, used this technique when frustrated by 



