THE IMPENETRABLE SEA 



forbids mention of more than a few of the numerous 

 varieties which hve in that vast area where waves and 

 atmosphere meet. 



Swordfishes and their near relatives might be hkened 

 to torpedoes, but any such comparison, however pic- 

 turesque, would be inadequate. It is in fact difficult to 

 conceive how such macabre creatures could possibly have 

 evolved by any of the processes usually associated with 

 nature. Superficially considered, the fearsome projection 

 from the swordfish's head may seem to be a weapon of 

 defence, but in the long process of evolution, and before 

 it became efficient, the fishes possessing it would surely 

 have been at a serious disadvantage in the struggle for 

 survival. And why should living torpedoes survive, any- 

 way? The devastating eflfect of the sixty miles an hour 

 impact of a swordfish on the hull of a wooden vessel 

 could only be equalled by man if he used some kind of 

 explosive, a super-ram in the form of another vessel 

 striking the hull at high speed, or a long series of blows 

 with a heavy hammer. The force involved seems wasted 

 when applied to smaller fish than the swordfish itself 

 (which the creature depends upon for food) yet it is 

 ridiculous to assume that swordfishes developed their 

 powerful weapons to attack ships, long before ships 

 existed ! 



Most of the fast-swimming fish use principles applied 

 in man's most modern submarines. For instance, numbers 

 of them have a sac-like chamber (the swim-bladder) 

 which contains gas. When the fish sinks into lower depths, 

 gas is extracted : when it rises towards the surface, gas is 

 pumped into the swim-bladder. The fish can therefore 

 rise or sink or remain at any depths it chooses. 



All man's inventions are foreshadowed in lower 

 creatures in one form or another. The ant uses a comb, 

 the earwig uses tweezers, the aphis has a vacuum- 

 cleaner, the ichneumon-fly its own drill, the snail its 

 file. But apart from land animals and insects, and 



42 



