120 



NORTH AMERICAN FAUNA 68 



feeding sea urchins should not occur." Evidence that this as- 

 sumption is not always true is presented under "Relative Values 

 of Sea Otter Foods." 



The method of ingesting green sea urchins varies according to 

 the size of the sea urchin and also somev^hat according to the 

 habits of individual otters. Stomach examinations and observations 

 of feeding otters indicate that some animals habitually ingest 

 more of the test than others. Small urchins are crushed by the 

 molars and usually at least part of the test is sv^allov^ed (fig. 65). 

 Large urchins may first be bitten v^ith the postcanines on one side, 



Figure 65. — Intact sea otter food organisms are shown at the top of columns 

 A to E, and partially digested fragments of the same species removed 

 from stomachs are shown below. A — six-rayed star (Leptasterias sp.) ; B — 

 green sea urchin (Strongylocentrotus drobachiensis) ; C — sea cucumber 

 (Cucumaria sp.) ; D — pearly monia (Pododesmus macro schisma) ; E — 

 mussel (Mytilus edulis) ; F — fragments of marine algae. Algae, which is 

 voided undigested in the feces, is not a food species but is eaten accidentally. 

 (KWK 1011) 



