no 



VV HALES 



Figure 66. Front view of lumbar vertebrae of a Bottlenose Dolphin and a Bottlenose Whale, 

 showing differences in length of spinous and transverse processes. 



Cetaceans is approximately one. In other words, most dolphins and whales 

 neither sink nor rise but float in the water. However, this is merely a 

 generalization, for w'e have already seen that there are whales, such as 

 the Sperm Whale and the Right Whale, whose carcasses rise to the surface, 

 while Rorquals generally sink to the bottom. Some dolphins are known to 

 rise while others are known to sink, after they are killed or dead. Dead 

 terrestrial mammals generally sink, and the same is true of hippopotami, 

 which are so heavy that they can walk along the bottom of a river. 



In whales, individual differences in this respect are probably due mainly 

 to differences in the thickness of the blubber. Flensed carcasses always 

 sink. Right Whales and Sperm Whales, particularly, have a relatively 

 thick layer of blubber, and so has the Humpback Whale which, though air 

 is always pumped into its carcass for safety, generally floats after it has 

 been killed. The carcasses of Blue and Fin Whales often float towards the 

 end of the whaling season, by which time their blubber has become much 

 thicker. Floating also depends on the extent to which the lungs are filled 

 with air. Thus animals which sink after death, e.g. Rorquals and 

 dolphins, can, thanks to the air in their lungs, float at the surface when 

 alive, with their blowholes just above the water. Two American scientists 

 (Woodcock and McBride) managed to demonstrate a clear difference in 

 the specific gravity of a dead and a living Rough-toothed Dolphin. 



The reader may have wondered what speeds these powerful swimmers 

 can develop. Sailors and whalers the world over have told us a great deal 

 on this subject, but before we discuss their figures, a few cautionary 

 remarks are needed. A point to be borne in mind in arriving at the correct 



