132 



WHALES 



Wa 



Maximum capacity of lungs 



Tidal air per lOOkg. of body weight 



^ 



Figure J^. Maximum capacity of lungs and tidal air per lOo kilograms of body weight in a 

 horse, a man, a seal, a sea-cow, a porpoise, a Bottlenose Dolphin, a Bottlenose Whale, 

 and a Rorqual. After data by Scholander and Irving. 



Otherwise they would perish, and the only question is how they get it. 

 It would appear that their method of respiration alone cannot supply the 

 required amount, for calculations have shown that, weight for weight, 

 about half as much air is contained in the lungs of Cetaceans as in those 

 of terrestrial mammals, while other calculations have shown that the 

 amount of oxygen Cetaceans use up in equal time is roughly the same. 

 Hence Cetaceans must have some special means of utilizing twice as much 

 oxygen from a given volume of air, and the only way in which they can do 

 so is by having blood that is adapted to this situation. In fact, the total 

 surface of their red blood corpuscles is very large, and it is here that we 

 must seek the key to our mystery. In Chapter 5 we shall return to this 

 subject in greater detail. 



