THE IMPENETRABLE SEA 



shark is greater than that of the blue whale — which some 

 authorities give as seventy or eighty feet, and some as 

 only sixty feet. We cannot dogmatize — the question can 

 only be settled by further investigation. 



Apart from size, the great shark and the blue whale 

 have little in common. The former is a fish, the latter 

 is a mammal. Both are regarded by zoologists as "harm- 

 less" — but again, we know so little of the great shark's 

 habits that the word, in its case, means nothing, while 

 the fact that the blue whale lives mainly on tiny creatures 

 and is apparently not aggressive does not mean much: 

 we should perhaps say "harmless if not attacked". 



Sharks can remain under the surface for any length of 

 time without coming up for air. Both whales and sharks 

 are absolutely helpless on land, although the whale is a 

 breathing animal. But the whale, unlike the shark, is also 

 helpless if it remains too long under the sea — it suffocates. 

 So far as our knowledge goes — and it is of course limited 

 regarding the habits of whales when far from land or 

 shipping — whales can stay under water for as long as one 

 hour and forty-five minutes. When the whale rises to 

 breathe it "spouts" or "blows". This action is often 

 described as the expulsion of water taken in at the mouth : 

 it is nothing of the kind. The whale has a nostril on the 

 highest part of its head, and through this it breathes out 

 forcibly when it comes to the surface, expelling air, not 

 water, although the expulsion causes a jet of water 

 vapour to rise above the surface of the sea. Man's know- 

 ledge of the whale shark is so meagre that stories of its 

 harmlessness may one day be regarded as worthless 

 legends. Its huge transverse mouth is certainly capacious 

 enough to receive a man. Its throat is larger than those 

 of other sea monsters — even larger than the throats of 

 other sharks within whose stomachs the bodies of humans 

 have been discovered. 



Whatever may be the truth regarding sharks and 

 their contacts with divers, even the most ferocious of 



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