ANIMAL LIFE IN THE SEA 163 



tropical part of the Atlantic, and in shallow bays or 

 lagoons. Though both spend their whole life in the 

 water, and are helpless outside it, yet both are definitely 

 littoral, for they feed upon the large algae, and could 

 therefore find no food in the open sea. The manatee 

 apparently takes a large variety of aquatic plants in 

 addition to algae. The animals are not nearly such good 

 swimmers as the Cetacea, and their heavy bodies and 

 massive bonies fit them for life near the bottom. The 

 hind-legs are entirely absent, but the fore-limbs may 

 touch the ground as the animals swim leisurely along 

 the bottom, and are also used in pushing food into the 

 mouth, and in carrying the young, which are suckled 

 above water. 



Of the littoral birds perhaps the most interesting are 

 the flightless penguins, which present the same features 

 as the seals in that, though pelagic for much of the year, 

 and having a perfect mastery of the water, they must 

 come on shore for breeding purposes. The absence of 

 any carnivorous land mammals in the Antarctic area, 

 and its inaccessibility, make it a perfect paradise for the 

 penguins, who resort to its rocks and beaches in millions 

 to breed, and have been described by all the Antarctic 

 expeditions (see Fig. 44). Quite comparable in habits, 

 though not related, was the extinct great auk (Alca 

 impennis) of the shores of the North Atlantic, which 

 was similarly incapable of fUght, and fell an easy 

 victim to man during the breeding-season. 



Of the other birds which feed in the sea and frequent 

 it, some, like certain of the seagulls, forsake it at the 

 breeding-season for inland regions. Others, hke httle 

 auks, guillemots, puffins, gannets, and so forth, breed 

 on the shore, choosing cold or inaccessible regions 

 for the purpose. Of the various adaptations to such 



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