FEEDING 



277 



Figure i§6. Central part of the left lower and upper jaws of the 

 Beaked Whale Mesoplodon grayi van Haast {Leyden Museum of 

 Natural History). Aote the tooth which has cut through the lower 

 jaw, and the row of teeth hidden in the gum of the upper jaw. 

 {Boschma, 1956.) 



~H- 



a Sperm Whale's stomach to find a giant squid some thirty-five feet long 

 (tentacles included) and weighing more than 400 lb., i.e. the weight of 

 two adult men and one child. 



Sperm Whales do not chew their food either but swallow it whole. 

 To seize their prey, they have 18-30 pairs of teeth in the lower jaw (Figs. 

 157 and 158), the two halves of which are fused over more than half of 

 their length (Fig. 159). The teeth of the lower jaw lie embedded in a 

 groove, in which a row of sockets can only just be distinguished, but 

 though the teeth are therefore poorly anchored to the bone, every whaler 

 who has tried to take a Sperm Whale tooth home as a souvenir will tell 

 you how difficult it is to wrest it from the exceptionally tough connective 

 tissue of the gum. In this way, the teeth are held firmly in position, and 

 whenever the Sperm Whale closes its mouth the conical ivory-coloured 

 tips fit exactly into a row of corresponding indentations in the palate of the 

 upper ja^v. While young teeth are sharp and gently curved, older teeth 

 may become so worn down by friction that they are quite blunt. (We have 

 seen that they lack enamel.) In the pulp cavity, and also in the otherwise 

 smooth dentine of the tooth, there often arise irregular rounded patches 

 of osteodentine. These were described in detail by Neuville (1935) and by 

 Boschma (1938). 



Oddly enough, the Sperm Whale's exceptionally good set of teeth does 

 not seem to play as important a part in its life as we might have thought. 

 When a young Sperm Whale is weaned and has to look for its own food, 

 the teeth have not yet broken through, and they do, in fact, only appear 

 when the animal has grown to about twenty-five feet, i.e. when it has 

 reached sexual maturity. Moreover, Sperm Whale teeth often show signs 



