116 



NORTH AMERICAN FAUNA 68 



fication of food species difficult or impossible. As the stomachs 

 were examined, a collection of unknowns was accumulated. Food 

 organisms found in various stages of mutilation in different 

 stomachs eventually furnished material that made possible the 

 recognition of small fragments or badly mutilated food in other 

 stomachs. The food species found in sea otter stomachs taken at 

 Amchitka are shown in table 13 and a general account of these 

 organisms and the sea otter's habits relating to their consumption 

 follows. 



Annelid worms were usually torn into pieces several centi- 

 meters long and the pieces swallowed with minor damage from 

 mastication. Considerable slimy mucus accompanied annelid re- 

 mains. 



Crabs were torn to pieces and usually the carapace was not 

 among the stomach contents. The larger legs and chelipeds were 

 usually thoroughly crushed. 



Among the mollusks that were found, various techniques of 

 ingestion were indicated. Small chitons were slightly crushed and 

 often swallowed nearly intact. Large ones (Cryptochiton stelleri) 

 were thoroughly crushed and torn, reducing them to small pieces. 

 The flesh of limpets was scooped from the shell and swallowed 

 nearly intact and the shell discarded. Rarely was a fragment of 

 limpet shell swallowed. 



Table 13. — Frequency of occurrence of food species in 309 sea otter stomachs 

 from Amchitka Island, Alaska 



Number of stomachs having item — 



Of 107 Of 20 Of 182 

 stomachs stomachs stomachs 

 February- October March- 

 Food organism April 1962 1962 April 1963 Total Percent 



Annelida - 



Ribbon worm Emplectonema 



sp .... 



Sand worm Nereis sp 



Lug worm Arenicola sp.— 



Total 



Arthropoda: 

 Crustacea : 



Olive green isopod Idothea 



(Pentidotea) 



Amphipods (probably 



incidental) 



Shrimp Sclerocrangon 



boreas 



Hermit crab Pagurus sp 



Crab: 



Cancer sp. - 



Telrnessus cheiragonus. . 

 Paralithodes? (larval ).... 

 Placetron wosnessenski. 



Hapalogaster sp 



Unidentified 



Shrimp unidentified 



Total. 



1 







1 





2 







2 





5 







5 





8 





5 



13 



2 



6 





3 



9 





5 





6 



11 





1 







1 





3 



3 



9 



15 





1 



5 





6 





1 



1 





2 





2 







2 





5 





1 



6 









5 



5 









4 



4 









1 



1 





24 



9 



29 



62 



7 



