96 



WHALES 



blubber so reduces its specific gravity that it has difficuhy in diving 

 normally. The Grey Whale, too, displays its flukes just before diving, but 

 not when swimming near the surface. All these characteristics, together 

 with the shape of the head, the profile of the back, the shape and size of 

 the dorsal fin, and particularly the shape of the 'blow' - the cloud of 

 vapour which the whale exhales - often enable whalers to identify the 

 species. Even so, Blue, Fin, and Sei Whales are not easily distinguished 

 except by very experienced whalers. 



The surfacing of many dolphins, and particularly of porpoises, is very 

 similar to that of Fin Whales (Fig. 54). The animals come up at an angle 

 of 30°, and depending on their speed, either the tip of the snout or the 

 blowhole emerge first out of the water. When they swim slowly, some 

 dolphins, such as the Boutu, can surface almost horizontally. 



What we have said so far applies to normal swimming only, but just 

 as we sometimes skip and dance rather than walk, whales too, often behave 

 extraordinarily. Thus it is said that Fin Whales occasionally swim on their 

 side when they are feeding. It is believed that these large animals cannot 

 turn very easily, and have to 'roll' instead. Many dolphins are real high- 

 jimipers; they sometimes shoot out of the water in a wide arc, and some- 

 times jump right up into the air, with their bodies almost perpendicular 

 to the water (Fig. 57). Sometimes they dive back into the water snout 

 first; at other times chest or belly first. The large whales, despite their 



Figure 52. Sperm Whale surfacing slowly. Mote blowhole {left) and dorsal 'binnp [right ). 

 Photograph : R. Stephan aboard M.S. Pool, New Guinea. 



