RESPIRATION I29 



motion. Admittedly, the relatively small surface area of dolphins is part 

 of the explanation, but it is by no means the whole story, which can only 

 be told after we have taken a closer look at the Cetacean lung. 



A mere comparison of its weight with that of the lungs of other 

 mammals would tell us very little; far more relevant is a comparison of the 

 respective lung-to-body weight ratios. Unfortunately, the measurements 

 involved are hard to come by. The lungs of a Blue Whale can weigh up 

 to a ton, and the animal itself more than loo tons. For accurate measure- 

 ments, the whole animal must first be cut up carefully, and this involves 

 much time and labour. Since whalers have little time to spare for such 

 tasks, most measurements have been carried out at land stations, where 

 the men are not in quite so great a hurry. Even so, it is astonishing that 

 enough time has been found to weigh as many as forty-six big whales to 

 date. The record is held by a Blue Whale, weighed by Winston in 1950. 

 The animal tipped the scales at 134-25 tons. Captain Sorlle measvired the 

 runner-up in 1926 at South Georgia: a Blue Whale weighing 122 tons. 

 The Japanese have done a great deal of work in this field, in order to be 

 able to establish an average weight. In 1950, Omura weighed 16 Sei 

 Whales and 10 Sperm Whales, and in 1956, Fujino weighed another 15 

 Sei Whales in another area. Much of our knowledge is also due to the 

 work of G. Crile, an investigator who devoted a good deal of time to 

 weighing the organs of many wild animals. The figures he obtained are 

 much more valuable for our purpose than the available wealth of data on 

 captive animals. It is thanks to Crile that we have what little information 

 there is on the weight of the dolphin's organs, though the Dutch whaling- 

 research group of the TNO organization has recently begun to do field 

 work in this sphere. 



From the available data, it would appear that the lungs of terrestrial 

 mammals represent 1-2 per cent of the total body weight, while the figures 

 for Rorquals, Sperm Whales, Pigmy Sperm Whales and Bottlenose 

 Whales are only o -6-0 -9 per cent. In dolphins and porpoises, however, 

 the figures are 1-6 per cent, the average being 3 -5 per cent. The great 

 differences between various dolphins are associated with the I'espective 

 duration of their dives. Thus the Bottlenose Dolphin which dives for longer 

 periods than the Common Dolphin also has bigger lungs. Porpoises, 

 according to Kleinenberg, fall half-way between the two, while the 

 figures for beavers, muskrats and seals would seem to resemble those for 

 terrestrial mammals. 



Now, while the relative weight of the Ivmgs is an important indication, 

 what is even more important is relative lung-capacity, i.e. the amount of 

 air that can be stored up in the lungs, and also the amount of tidal air, 

 i.e. the air inhaled and exhaled with every normal breath. However, it is 



