WHALES 



Figure 162. Lower jaw of Fin 

 Whale used as gateway to the 

 vicarage at Stamp near Haders- 

 lev [Denmark). 



do not chew their food, they naturally have comparatively weak jaw 

 muscles and a simple jaw joint which allows the jaws to move in a vertical 

 direction only, while their lower jaw has a simpler structure than that of 

 terrestrial mammals. Certain processes, e.g. the coronoid process and the 

 angular process, which play such an important part in attaching the 

 muscles which move the lower jaw, were still well developed in Archaeo- 

 cetes, but are greatly reduced or entirely absent in all other Cetaceans, 

 and particularly in those Odontocetes which feed on cuttlefish, and in all 

 Mysticetes, since Mysticetes do not have to seize their prey but need 

 merely open and shut their mouths. In the course of 35 million years, the 

 lower jaw of these animals has become an extremely simple, arched clasp. 

 In Rorquals the processes can still be distinguished, but in Right Whales 

 they have been reduced to insignificant stubs, and the jaw joint has an 

 extremely simple globular head. The lower jaws of Mysticetes are bent 

 strongly outwards to make room for the baleen. This phenomenon is most 

 striking in Right Whales, whose jaw-bones were often used for gate-posts 

 by whalers of earlier times (Fig. 162). In Holland this custom has recently 

 been revived, and in Schiermonnikoog there is a twenty-one-foot gate made 

 from the jaws of a Blue Whale. 



Between the two halves of the lower jaw lies the bottom of the mouth, 

 which, as we have seen, has longitudinal grooves in Rorquals, whose 

 mouths can be considerably distended. We have also seen that these 

 animals need large mouths for ingesting considerable quantities of krill 

 with each gulp. They can do this all the better by virtue of a number of 



