60 



NORTH AMERICAN FAUNA 74 



FETUS (First pelage) 



CONE 



LANUGO 



CLUB 



SHED 



FETUS-NEONATE (Second pelage) 



CONE 



NATAL 

 E CLUB SHED 



NEONATE (Third pelage) 



// POSTNATAL 



CONE CLUB 



1 year + older 

 ( Adult pelage) 



CLUB 



SONDJFMAMJJASO 

 MONTH 



Fig. 40. Sequence of events in development of the lanugo, natal, and post-natal pelages 

 of Pacific walrus fetuses and calves, in relation to the annual molt of adult-t\pe pelage in 

 the older animals. 



before the time of birth. This is different from the lanugo of Phocidae but 

 some\\ hat like that of the northern fur seal (Otariidae), if Belkin's (1964) analysis 

 is reliable (see below ). This first (prenatal) pelage is markedly different from the 

 later pelages of the walrus, in form as well as in pigmentation. In general, the 

 hairs resemble underfur. rather than guard hairs, except that they usually occur 

 singh' rather than in bundles. To some extent, the first pelage resembles that of 

 other pinnipeds, in that the hairs are fine, sinuous, and largely unpigmented (cf . 

 Belkin 1964: Stutz 1966). The second (natal) pelage closely resembles that of the 

 adults, except that the hairs are somewhat shorter and less robust. The third 

 (postnatal) pelage is essentially the same as the second. 



The walrus may be the only pinniped that bears three different pelages and 

 undergoes two true molts within 1 year of fetal to early postnatal life (Fig. 40). 

 Although Belkin (1964) indicated a similar schedule of events in the northern fur 

 seal, true molt of the white lanugo before de\-elopment of the natal coat was not 

 detected by Scheffer (1962) in his scrupulously detailed study of the fetal pelage 

 of that species. On that account, and because of some doubts about timing. Ling 

 and Button (1975) have questioned Belkin's results. 



Pelage and Annual Molt of Adults 



The pelage of adult walruses is coarser and less dense than that of the calves 

 (Table 8; Figs. 37 and 38). \ et it imparts the same furry or velvet}' appearance to 

 the bod>- surface (Fig. 32). When dry. the hairs are erect and the tips tend to 

 cur\ e forward, hiding from view most of the topographic details of the skin; 

 when wet, the\- lie flat against the skin. On the bosses of the neck and shoulders of 

 adult males, the hair often is \'ery sparse or absent, exposing the surface of the 

 skin to \-iew (Fig. 32). 



More than 90 of the hair canals of adults bear only a single primary or guard 

 hair; canals with more than two hairs are scarce (Table 8). Where two or three 



