THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 27 



Among pinnipeds, which subsist entirely on flesh, the ratio 

 (small intestine length) 



ranges from 5.2 in Monachus to 42.0 in 



nose-tail length 



Mirounga (King, 1964). The sea otter, which subsists on marine 

 invertebrates and fish, falls within this general range. Apparently 

 animals which feed primarily on warm-blooded vertebrates have 

 relatively shorter intestines. The above ratio is 5 for the dog and 

 cat (King, 1964). 



Organ weights 



The relative sizes of body organs may give a clue to the adap- 

 tations of an organism to its environment. I have undertaken no 

 physiological studies, but the following comparisons of the relative 

 size of selected body organs of the sea otter with those of other 

 mammals indicate that such studies would be interesting and 

 desirable. 



Organs were weighed on a balance having a maximum capacity 

 of 15 kg. Sample organ weights were obtained from six adult 

 male and nine adult female sea otters that were shot while ap- 

 parently in normal health at Amchitka Island and other areas 

 (table 8). Comparison of the organ weight expressed as percent 

 of body weight indicates that in some respects the sea otter is quite 



Table 8. — Weights of body organs in nine adult female and six adult male 



sea otters 



[Weight in grams. All apparently healthy adults shot at Amchitka Island, except 60-4 to 60-8 

 which were shot in the Shumagin Islands and off Unimak Island] 



Liver Heart Kidney Spleen 



Collection Body Percent Percent Percent Percent 



number weight of body of body of body of body 



Weight weight Weight weight Weight weight Weight weight 



Females : 



62-2 ....._ 21,770 1,219 5.60 182 0.84 409 1.88 65 0.30 



62-6- _ 20,410 1,130 5.54 152 .74 340 1.67 59 .29 



62-8 19,950 1,135 5.69 130 .65 367 1.84 65 .33 



62-11 20,410 1,730 8.48 126 .62 346 1.69 90 .44 



62-12_ 23,130 1,632 7.06 160 .69 425 1.84 90 .39 



62-15....- 21,300 1,226 5.76 135 .63 385 1.81 92 .43 



62-19 19,050 955 5.01 134 .70 315 1.65 85 .45 



62-20-_ _ - 17,690 1,000 5.65 142 .80 350 1.98 58 .33 



60-4 __ 32,500 1,450 4.46 175 .54 470 1.45 150 .46 



Mean.-- 21,800 1,275.2 5.85 148.4 .68 378.5 1.74 83.8 .38 



Males : 



62-1 - - 29,940 1,479 4.94 185 .62 700 2.34 86 .29 



62-10- 36,290 2,685 7.39 211 .58 821 2.26 177 .49 



60-5 35,500 1,650 4.65 230 .65 870 2.45 100 .28 



60-6- 45,000 2,390 5.31 270 .60 1,120 2.49 110 .24 



60-7- 41,300 1,860 4.50 272 .66 997 2.41 113 .27 



60-8.. 41,700 2,086 5.00 227 .54 1,026 2.46 113 .27 



Mean 38,280 2,025 5.29 233 .61 922 2.40 116 .31 



Mean, all ..28,410 1,575 5.67 182.1 .66 596.1 2.01 96.9 .35 



