FEEDING 291 



digestive juices and of absorbing digested foods, and the intestine must 

 therefore gi-ow longer. It is not at all clear why the Sperm Whale is so 

 abnormal in this respect, since its diet of cuttlefish is no different from that 

 of many other Cetaceans whose intestines are about the length we would 

 expect. 



If we compare the above figures for Cetaceans with those for mammals 

 of comparable external dimensions, we find that the respective figui^es are: 

 man - 650 per cent; lion - 390 per cent; sheep - 3,000 per cent; seal - 

 1,600 per cent as against the smaller dolphin's average of 1,700 per cent. 

 Clearly carnivorous animals have a short, herbivorous animals a long, and 

 omnivorous animals an intermediate intestine. Experiments on various 

 mammals have shown that fish-eaters have much longer intestines than 

 meat-eaters, which may be due to the fact that, while the latter spurn 

 part of the skin and bones of at least their bigger victims, the former, 

 and also the Killer Whale, leave nothing behind. It is quite possible, 

 therefore, that the digestion and absorption of certain substances found in 

 the skin and the skeleton of the prey demand a much larger intestinal 

 surface in the captor. However, too little is known about the digestion 

 of Cetaceans for any final pronouncements to be made on this 

 subject. 



The Cetacean pancreas seems to be similar to that of most mammals, 

 both in situation, structure, function and relative weight (i.e. o • 1-0-2 per 

 cent in small, and o -03-0 -15 per cent in large Cetaceans). The organ has, 

 however, not yet been investigated sufficiently, an omission which is the 

 more regrettable since the enzymes it secretes are of great practical 

 interest. In Germany, for instance, the enzyme has been used successfully 

 for leather tanning, and in Japan for other industrial purposes. Investi- 

 gators are hampered by the fact that the pancreas must be removed 

 immediately after death and that it must then be refrigerated at 

 once. 



The Cetacean pancreas generally has one, but occasionally more than 

 one, duct which combines with the bile duct of the liver into one passage 

 entering the duodenum. In many mammals, man included, a branch of 

 the bile duct runs to the gall bladder where part of the bile is 

 temporarily stored, to be poured into the intestine in large quantities 

 whenever it is needed. The fact that all Cetaceans are completely 

 devoid of a gall bladder was already known to Aristotle and Pliny, 

 so that man has known about it for over 2,000 years, though the 

 reason why remains obscure to this day. This is a strange gap in our 

 knowledge, the more so since a great many other mammals belonging to 

 different orders are also devoid of this organ. 



No discussion of the Cetacean digestive system would be complete 



