ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



149 



Fig. 97. Three kinds of benthic invertebrates commonly found in stomachs of Pacific 

 walruses: (a) Golfinf^ia mar^aritacea; (b) siphons of Hiatella arctica; and (c) Priapulus 

 caudaUifi. Scale in centimeters. (Photos by F. H. Fay) 



Echiurida. — One of the invertebrates most often found in the ingesta of 

 walruses in the Bering Sea is the nonsegmented worm Echiurus echiiirtis (Fig. 

 96c). Because of its delicate structure, it seldom is found intact in the alimentary 

 tract but very often is indicated there and in the feces by the presence of its 

 distinctively hooked, gold-colored setae. In the feces of bulls at Round Island in 

 June, these setae were nearly the only organismal remains found, suggesting that 

 Echiurus is a major prey item in that area, at that time. S. W. Stoker and I found 

 it to be one of the three or four most common items in the feces of adult cows and 

 subadults in the St. Lawrence concentration area during March, April, and 

 May. This worm, up to 15 cm long and about 2 cm in diameter, resides in a 

 shallow, U-shaped burrow in the mud. It seems to be very abundant and widely 

 distributed in the Bering and Chukchi seas, at depths from the littoral zone to at 

 least 80 m. 



Priapulida. — A single species, Priapulus caudatus, of this phylum of 

 nonsegmented worms is found in the Bering and Chukchi seas, where it inhabits 

 silty bottom types at water depths from 5 m to at least 50 m. Like the worms 

 mentioned above, Priapulus is a burrower in the upper layers of bottom 



