TEETH 



249 



TEETH 



In sperm whales the functional teeth are restricted to the lower jaw. The data in Table 8 seem enough 

 to show that, at least in females of the North Atlantic, these teeth do not erupt until the whale is 

 between 8-4 and 9-5 m. long, that is, between 28 and 3 1 ft. This agrees well with Bennett's observation 

 (1836, p. 127) that 'when the young cachalot has attained a length of 34 ft., its teeth are perfectly 

 formed, though not visible until it exceeds 28 ft.'. For Azores males, where less data are available, 

 Table 8 only suggests that the teeth erupt at some length greater than 7-8 m. (26 ft.) and less than 

 ii-o m. (36 ft.). However, Matthews (1938, p. 122) mentions southern males of 8-8 and 10-4 m. with 

 erupted teeth, so it is likely that males and females cut their teeth at similar body lengths. 



Table 8. Eruption of the mandibular teeth in whales examined at Horta between 1949 and 1954. The 

 letters 'i' and'tn' indicate whether the whales were sexually immature or mature respectively. Males larger 

 than ii-o m. had erupted teeth. Females larger than 9-5 m. had erupted teeth and were sexually mature 



No. of whales 



Lengths in 

 metres 



6-58 



7-5 

 7-8 



ii-o 



n-3 



6-58 



7-2 



7-3 



7-4 



7-5 



7-6 



77 

 7-8 



7-9 



Teeth not 

 erupted 



Teeth 

 erupted 



Males 



1 f 

 1 i 

 1 i 



1 2 

 1 m 



Females 



1 r 

 1 i 



1 1 

 1 i 



* Whales F306, £ and F307 $, each 6-58 m. long, were calves. 



f In whale F89 the teeth were just erupting. 



J Whale F198 was in its first pregnancy. 



§ In one of these whales (F94) the teeth were just erupting and the whale was in its first pregnancy. 



Sperm whales of the North Atlantic are weaned when about 67 m. long (p. 275), so it is clear from 

 Table 8 that the teeth are not cut until some long time after the age at weaning. The data in Table 8, 

 so far as they go, suggest that the teeth of females erupt at a mean body length of about 8-8 m. 

 (29 ft.), which is also the mean length at which females become sexually mature (p. 265). It may be 

 that a causal connection exists between teething and puberty, although this possibility is not entirely 

 supported by the notes and footnotes on sexual maturity and pregnancies in the table. 



Like female Ziphioid whales, where functional teeth never erupt, young sperm whales with still 

 toothless jaws seem to find no difficulty in securing the squids which are their staple food: of those 

 nine Azores whales past weaning which had unerupted teeth, eight had stomachs containing small 

 or moderate amounts of squids, and the stomach of the ninth (Whale F308, 7-2 m.) was crammed full 

 with the bulky squid Cucioteuthis unguiculatus. 



