36 



NORTH AMERICAN FAUNA 74 



Table 5. Relative weights of body parts from Pacific walruses taken March 

 to June, 1958-72. 



Males^ Females^ 



Part No. weighed % live weight No. weighed % live weight 



Skin and blubber 



4 



37.9 -49.4 



2 



27.6 ^2.4 



Head (with skin, tusks) 



4 



1.8 - 3.8 



2 



2.5 - 4.3 



Bone and muscle*^ 



4 



20.6 -40.9 



1 



26.4 



Skeleton^ 



1 



4.3 



1 



3.6 



Blood and other fluids 



3 



8.2 - 8.5 



0 



- 



Heart 



5 



0.50- 0.56 



2 



0.80- 0.85 



Trachea and lungs 



3 



1.1 - 1.6 



2 



1.9 - 2.2 



Liver 



5 



1.5 - 4.0 



2 



2.8 - 3.2 



Spleen 



5 



0.15- 0.28 



1 



0.14 



Pancreas 



2 



0.20- 0.37 



1 



0.25 



Stomach (empty) 



4 



0.49- 0.76 



1 



0.74 



Intestine (empty) 



4 



2.4 - 3.3 



1 



3.8 



Kidneys 



5 



0.41- 0.65 



2 



0.49- 0.63 



Adrenal glands 



1 



0.08 



0 





Penis and testes 



2 



0.21- 0.38 







Uterus and ovaries 







2 



0.8e- 2.5 



^Live weights, 1,225 to 1,557 kg. 



bLive weights 635 to 914 kg. 



<=Postcranial skeleton and attached musculature. 



<^Skull with tusks, plus postcranial skeleton, thoroughly cleaned and dried (museum grade). 

 ^This specimen not pregnant; the other about 1 day postpartum. 



489 to 1,040 g (mean, 874.1 g). The longest baculum, from an animal of 

 unknown age, was 62.4 cm; the heaviest weighed 1,070 g. The length of the 

 baculum at birth was about 19% of that in the adult; the weight was about 

 0.5% of that in the adult (Fig. 23). 



In actual size, as well as in relation to the body, the baculum of the adult 

 Pacific walrus is the largest in any living mammal, being equal to about 18% of 

 the standard length and about 0.1% of the whole body weight (Scheffer and 

 Kenyon 1963). It increases 5.3 times in length and about 187 times in weight 

 from birth to adulthood. Its weight-.length relationship is divisible into at least 

 four distinct phases of relative growth (Fig. 24), corresponding to the periods of 

 infancy (0 to 3 months), juvenility (1 to 2 years), preadolescence and adolescence 

 (3 to 10 years), and subadult and adulthood (>10 years). The greatest gains in 

 weight per unit of increase in length take place in the first and last phases, which 

 make up the initial period of ossification and the final period of greatest increase 

 in density. In the intermediate phases, the baculum grows relatively more in 

 length than in weight. During the final phase, it is transformed from a relatively 

 slender, spongy bone to one that is stout and strong. 



Testes 



Testes from 197 animals, including many calves and fetuses, were weighed to 

 the nearest gram, without the epididymides, and their length was measured to 

 the nearest millimeter. Although they usually were slightly unequal in size and 



