ANIMAL LIFE IN THE SEA 159 



animals, are represented in the shore waters by many 

 species — by more than in the open ocean. But, it 

 may be asked, if these algae have no attachment to 

 a substratum, how do they contrive to remain in 

 the shore waters, in spite of currents and tides which 

 must tend to sweep them seawards ? The answer 

 is apparently that myriads are so swept out into 

 the ocean, but there they degenerate, and probably 

 do not live long. Produced in the shore waters, their 

 destiny may be to serve as food for the pelagic animals 

 of the open seas, but they no more form a true part 

 of the hfe of the pelagic area than does that shore- 

 bom weed which floats at the surface of the Sargasso 

 Sea for a period, ere it perishes and is replaced by new 

 fragments torn ofE by the currents. 



Of the physical peculiarities of the httoral area the 

 constant movement of the waters is characteristic. 

 Tides and currents, in all the open seas, ensure that no 

 stagnation shall occur, and thus keep the water sweet, 

 and bring constant supplies of food and oxygen. It is 

 this constant movement which helps to give the shores 

 of the oceans so much richer a fauna than the shores of 

 lakes, or of enclosed seas like the Mediterranean or 

 Black Sea. The constant movement brings with it 

 also a danger, whose influence is manifest in several 

 ways. Some of the shore forms are swift swimmers, 

 strong to stem the tide, and yet, notwithstanding their 

 strength, the shore naturalist knows that off many 

 coasts he is sure of a rich harvest when wind enforces 

 tide or current, for the beach at certain seasons is 

 strewn with flotsam and jetsam. Majiy shore fish, the 

 strong cuttles among molluscs, powerful forms like 

 porpoises and dolphins and even whales — there are 

 times when the strength of these avails them nothing 



