ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



31 



straight line from nose to tail with the animal lying on its belly and the spine 

 arched (Gromov et al. 1963). 



Table 2. Number of completely formed cementum layers in cheek teeth of 

 some walruses of known age, reared in captivity. 



Specimen and source' 



Sex 



Age 

 (years) 



No. of 



layers 



Moose, San Diego Zoo 



(LACM M1685) M 

 Aivok, New York Aquarium 



(AMNH 203342) M 

 Bosco, San Diego Zoo 



(EDM 477) M 

 Hagenbeck Tierpark 



(ZMUH 1226) M 

 Snowball, San Diego Zoo 



(LACM M1784) F 

 Oswald, San Diego Zoo 



(LACM Ml 785) M 

 Butch, San Diego Zoo 



(LACM M1786) F 

 Seekii, New York Aquarium 



(AMNH 203340) M 

 New York Aquarium 



(AMNH 203343) F 

 Herbert, New York Aquarium 



(AMNH 164116) M 

 Hagenbeck Tierpark 



(ZMUH 1587) M 

 Ookie, New York Aquarium 



(AMNH 203341) F 

 Copenhagen Zoological Garden 



(ZIUK 920) F 

 Priscilla, Marineland 



of the Pacific F 

 Woofy, Marineland of 



the Pacific M 

 Hagenbeck Tierpark 



(ZMUH 3099) F 

 Copenhagen Zoological Garden 



(ZIUK 748) F 

 Raudi, Hagenbeck Tierpark 



(ZMUH 5925) M 



0.3 

 0.4 

 1.1 

 1.2 

 1.2 

 1.2 

 1.3 

 1.3 

 1.3 

 1.9 

 2.4 

 3.4 

 5.2 

 6.3 

 7.0 

 7.1 

 7.6 

 15.3 



^AMNH = American Museum of Natural History, New York; EDM = "Elack Douglas" 

 Collection, National Marine Mammal Laboratory, Seattle; LACM = Los Angeles 

 County Museum, California; ZIUK Zoological Institute, University of Copenhagen, 

 Denmark; ZMUH = Zoological Museum, University of Hamburg, 

 Germany. 



