152 



NORTH AMERICAN FAUNA 74 



Fig. 100. Soft shelled (molting) crabs, Hyas coarctatus, from the stomach of a Pacific 

 walrus. Scale in centimeters. (Photo by F. H. Fay) 



two or three most common items in the ingesta. At least 15 genera of crustaceans 

 have been found in the stomach contents of walruses taken in spring and summer 

 in the Rering and Chukchi seas. These included mysids, amphipods, shrimps, 

 pagurid (hermit) crabs, lithodid crabs, and brachyuran crabs. All of the 

 represented genera reside on or in the uppermost strata of bottom sediments at 

 water depths ranging from about 5 m to more than 1,000 m. All of the pagurid 

 and brachyuran crabs that I found in walrus stomachs were in the soft-shelled 

 stage of their molt (Fig. 100), suggesting that they are taken selectively, perhaps 

 on a very seasonal basis. 



Echinodermata. — At least five species of holothurians (sea cucumbers) have 

 been found in the stomach contents of the Pacific walrus. Some of these occurred 

 frequently enough and in large enough volume to indicate a high level of 



