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NORTH AMERICAN FAUNA 68 



R. L. Rausch (letter, 15 Sept. 1967) states: 



More recently, Corynosoma macrosomum Neiland, 1962, has been described 

 from a sea otter from Prince William Sound, and a single specimen evidently- 

 representing this species had been collected earlier from the same host from 

 Simeonof Island (see Neiland, 1962). Cestodes collected by K. W. Kenyon 

 from sea otters from Amchitka Island have been identified provisionally as 

 Diplogonoporus tetrapterus (von Siebold, 1848) (Rausch, 1964) ; this species 

 also was recorded from a sea otter from Prince William Sound. 



In general, these helminths probably affect the host little, if at 

 all (Rausch, 1953). However, two species. Microphallus pirum and 

 Terranova decipiens, were considered to be pathogenic. The cuti- 

 cular spines of the former evidently cause mechanical injury to 

 the intestinal mucosa, and, when the trematodes are abundant, 

 severe enteritis may result. Immature specimens of T. decipiens 

 frequently penetrate the intestinal wall and enter the body cavity, 

 where other organs may be invaded. Peritonitis following such 

 perforations may result in the death of the host. 



During the 1955-63 study period, I made gross examinations 

 of about 50 otters believed to have been in good health when killed 

 at Amchitka. Although both T. decipiens and M. pirum were found, 

 there were no gross lesions in the infested animals. In November 

 of 1957, Dr. Kenneth L. Binkley examined seven adult otters at 

 Amchitka, only one of which appeared to be in ''poor" condition 

 when captured. Only the ill animal was infested with an appreci- 

 able number of T. decipiens (65 worms) and M. pirum (many 

 worms), but there was no sure indication that this animaFs poor 

 condition was a result of parasite infestation. Problems encoun- 

 tered v^ith T. decipiens are discussed under 'In Captivity." 



In 1959 the stomachs of otters found dead on beaches were ex- 

 amined when possible. Among 27 juveniles, 2 contained T. decipiens 

 and among 14 adults, 5 were infested. In none of the animals ex- 

 amined were helminths found in the coelom and no instance of 

 perforation caused by helminths was noted. The animals, in most 

 cases, had been dead for several days before they were examined. 

 Peritonitis caused by perforation of the gastrointestinal tract 

 would probably have been detected. Examination of sample areas 

 of the small intestine revealed moderate to light infestation in 

 some animals, but for M. pirum diagnosis was considered un- 

 satisfactory because of decomposition. In addition, this parasite 

 inhabits crypts in the wall of the small intestine and is not easily 

 detected in gross examination. 



K. A. Neiland (letter, 9 July 1962) examined the intestinal tracts 

 of 8 adult sea otters chosen at random from 150 animals that were 

 shot in the spring of 1962 at Amchitka. In these he found a total 



