THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 29 



upon which some otters feed almost exclusively, are isotonic, or 

 nearly so, with sea water (Sverdrup, Johnson, and Flemming, 

 1942, p. 269). 



Fisler (1962) demonstrated that even a mouse (Peromyscus 

 sp.), that was adapted before capture to a salt marsh environ- 

 ment, survived when given sea water exclusively. 



Slijper (1962, p. 314) considers that the kidneys of cetaceans 

 (from 0.44 percent to 1.1 percent of body weight) are, because 

 of great body size, exceptionally large. In general, a large kidney 

 appears to constitute an important aspect of mammalian adap- 

 tation to the marine environment. 



Spleen. — In the sea otter the spleen is about 0.35 percent 

 of total body weight, which is similar to "0.3 percent in most 

 other mammals" (Slijper, 1962, p. 175). In 62 female fur seals 

 similar in size to the sea otters studied, Scheffer (1960) found 

 that the spleen was from 0.11 to 0.31 percent of body weight. 

 Thus, in the sea otter and river otter (0.46 percent, Jensen, 1964) 

 the spleen is relatively large. 



Although the mean percentages of organ size to body weight 

 of all sea otters studied were used in the foregoing general dis- 

 cussion, it appears that in the male, which is larger than the 

 female (see Body Measurements) the kidney is relatively larger 

 than in the female. Also, the spleen of the female is slightly larger 

 than in the male (table 8). 



Body temperature 



The body temperature of two apparently healthy animals, a 

 juvenile male (59-156) and an adult female (59-157), were ob- 

 tained when both had lost consciousness after injections of 

 "Lethol" (proprietary name for a compound containing N-amyle- 

 thyl-barbituate, sodium sec-butylethyl-barbituate, isopropyl alco- 

 hol, and sodium carbonate). The deep body temperatures (intra- 

 cardiac insertion of the thermometer before cardiac activity 

 ceased) and rectal temperatures were the same. The temperature 

 of the juvenile male was 38.0° C. (100° F.) and that of the adult 

 female was 37.5° C. (99° F.). 



Body temperature may drop before death under certain con- 

 ditions. On 1 April 1959, at Amchitka Island, an emaciated adult 

 female (59-98) was lying on a bed of grass above the high 

 tide line, breathing but unconscious. Her intracardiac temperature 

 was 28.0° C. (84° F.). An autopsy revealed extensive enteritis. 



During an experimental transplant, observations were made of 

 a juvenile subjected to unusual stress. The otter, a female about 



