II 



Metabolism 



A LL CETACEANS are gluttons, and the Killer Whale can swallow 

 /_\ meals of thirty seals at a time (see Fig. 154). In the Aquaria in 

 _L. A Florida and California, Pilot Whales are fed 45-60 lb. offish and 

 cuttlefish, while Bottlenose Dolphins (and Pacific White-beaked in 

 Marineland, California) consume 'only' 22 lb. offish a day. They could 

 easily eat more still, since the dolphins which were kept in the New York 

 Aquarium ate 65 lb. of fish a day. Porpoises, too, need a large supply of 

 food. Dudok van Heel found that, in order to keep his animals in good 

 condition, he had to feed them 22-25 ^b. of mackerel daily. Nishimoto and 

 his colleagues removed 450 lb. of krill from the stomach of a forty-foot 

 Sei Whale, which the animal must have swallow^ed shortly before, as the 

 small shrimps were still c|uite fresh. The stomach of an Antarctic Blue 

 Whale was found to contain nearly one ton of krill (Fig. 167), and we have 

 every reason to assume that this quantity did not represent its full daily 

 ration. 



Looking at Fig. 131, you might say that this is not surprising, since 

 animals 1,600 times our own weight must obviously eat correspondingly 

 large quantities of food. Actually, things are not quite as simple as that. 

 The inhabitants of Lilliput, when they found that Gulliver was twelve 

 times their height and therefore weighed 12^ times their w^eight, were 

 WTong to think that he would consume 1,728 times as much food as they 

 did — he had a much more economical metabolism than his small hosts. 

 True, a horse eats more than a mouse, but if we work out how much food 

 it needs per pound of body-weight, it appears that the mouse eats about 

 twenty-five times as much as the horse. 



To understand this strange phenomenon, we must first ask ourselves 

 w^hy animals have to eat at all. An adult human being who has stopped 

 growing needs food to replenish worn-out tissues. For instance, our skin 

 and the lining of our intestines are continuously exposed to frictional 

 effects, and thousands of red blood cells wear out every day. However, all 



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