CETACEANS 



WHALES, DOLPHINS AND PORPOISES 



(Cetacea) 



FEW persons associate whales with the four-footed beasts of 

 the land. So modified are they for the peculiar life that they 

 lead that practically no external resemblance to their true kindred 

 remains, and it is not surprising that the popular mind classes 

 them as fish, to which, however, they bear no relationship. 



Whales are practically devoid of hair, which is characteristic 

 of most mammals, its place in retaining the heat of the body 

 being taken by the thick coating of fat or "blubber" lying just 

 beneath the skin. There is no external trace of hind limbs and 

 the fore-limbs are modified into flat flippers for swimming, while 

 the tail is flat and forked like that of a fish, but it is flattened 

 horizontally instead of vertically. There is practically no neck 

 and the head, which is often very large, joins directly with the 

 body. It is but natural, therefore, that the bones of the neck are 

 very short and often joined solidly together. Whales have no 

 close relationship with any other group of mammals and even 

 the oldest fossil whales that have been discovered present much 

 the same structure as the living species. Though they were 

 undoubtedly descended from some form of land mammal, the 

 change to an aquatic life must have taken place at a very remote 

 period. As has been suggested, the immediate ancestors of the 

 whales probably became adapted to a life on the shores of rivers 

 and acquiring the habit of swimming were eventually carried out 

 to sea, where peculiar environment has brought about their pre- 

 sent structure. 



The cetaceans are entirely carnivorous, and their food 

 generally consists of small mollusks, shrimps and fishes. They 

 frequently associate in companies or "schools" and are for the 

 most part inoffensive and rather timid. In size they vary from 

 the smallest porpoises, somewhat less than ten feet long, to the 

 largest whales which reach a length of sixty to eighty-five feet 



tr 



