CHAPTER VIII 



LIFE IN THE OCEAN : ANIMALS 



Marine animals may be divided into those 

 that are warm-blooded and those that are 

 cold-blooded, or better still into animals 

 whose blood is usually at a more or less 

 constant temperature whatever the external 

 temperature may be, and animals whose 

 blood-temperature is always the same as, 

 or very little above, the temperature of the 

 water in which they are living. To the warm- 

 blooded animals belong all the marine air- 

 breathing mammals, such as whales, porpoises, 

 dolphins, seals, walruses, etc., the modern 

 whales being the largest creatures that have 

 ever lived on our earth. All these mammals 

 have descended from terrestrial species which 

 have adapted themselves to an aquatic mode 

 of life. In these marine mammals the blood- 

 temperature ranges from 98° to 104° F., and 

 does not sensibly vary whether they be found 

 in the ice-cold waters of the polar regions or 

 the warm waters of equatorial seas. If some 

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