78 



WHALES 



Figure 57. Left view of first 

 and second caudal vertebrae of 

 a Beluga. In this Odonlocete 

 the arterial grooves run behind 

 the transverse processes and 

 enter them from the rear. 

 (Slijper, 1936.) 



Squalodontidae, which are extinct, Miocene specimens of all extant Odonto- 

 cetes are known, some with fairly symmetrical and others (e.g. the 

 ancestors of the Sperm Whale) with asymmetrical skulls. 



Now we have dealt not only with the question of whale's limbs, but 

 with his ancestry also. But we are still on deck of our factory ship right 

 next to a freshly-killed whale, and we must take the opportunity of 

 examining the rest of the carcass before the men hack it into a thousand 

 pieces and throw it into the boilers. 



Let us take a closer look at the animal's shape. If we stand close by, its 

 bulk is too great for an overall view, and so we must climb up to a vantage 

 point on the afterdeck from which we can appreciate its beautifully 

 streamlined contours, so reminiscent of a torpedo. We know that this shape 

 offers minimum resistance to the water and thus guarantees maximum 

 speed. 



The shape is not the same in all Cetaceans (Fig. 41). The Right Whales 

 are a little more rotund, although they are certainly more streamlined in 

 their natural habitat than the formless mass we sometimes find at land 

 stations. The Rorquals, too, which look so squat when they lie on deck, 

 are in fact very slim - much slimmer even than some dolphins and 

 porpoises, whose maximum girth lies much farther back and whose tails 

 are not so slender. 



The heads, too, of the different Cetaceans show very marked differ- 

 ences, that of the Rorqual being fairly pointed, while those of porpoises 

 and dolphins are much blunter, since despite their long and pointed 

 snouts, their foreheads are bulbous (Figs, ig and 99). This is due to the 

 presence of a thick, hard cushion above the snout, sometimes caused by a 

 thickening of the blubber, but sometimes due to the presence of much 

 harder and tougher connective tissue containing fat cells (cf. the Sperm 

 W' bale's spermaceti case). A great deal of study is still needed before 

 scientists have a clear idea of the relationship between shape and water 



