222 THE FOUNDATION'S OF ZOOLOGY 



The seals pursue and destroy fishes ; the sea-elephants and 

 walruses live upon mollusks; the whales, dolphins and porpoises 

 and the marine reptiles all feed upon animals, and most of them 

 are fierce beasts of prey. 



There are a few fishes that pasture in the fringe of seaweed 

 which grows on the shore of the ocean, and there are some that 

 browse among the floating tufts of algae upon its surface, but most 

 of them frequent these places in search of the small animals 

 that hide among the plants. 



In the Chesapeake Bay the sheepshead browses among the 

 algae upon the submerged rocks and piles like a marine sheep, 

 but its food is exclusively animal, and I have lain upon the edge 

 of a wharf watching it crunch the barnacles and young oysters 

 until the juice of their bodies streamed out of the angles of its 

 mouth and gathered a host of small fishes to snatch the fragments 

 as they drifted away with the tide. 



Many important fishes, like the cod, pasture on the bottom, 

 but their pasturage consists of mollusks and annelids and Crustacea 

 instead of plants, and the vast majority of sea-fishes are fierce 

 hunters, pursuing and destroying smaller fishes, and often exhibit- 

 ing an insatiable love of slaughter, like our own bluefish and the 

 tropical albacore and barracuda. Others, such as the herring, feed 

 upon smaller fishes and the pelagic pteropods and copepods; and 

 others, like the shad, upon the minute organisms of the ocean ; but 

 all, with few exceptions, are carnivorous. In the other great groups 

 of marine animals we find some scavengers, some which feed upon 

 micro-organisms, and others which hunt and destroy each other, 

 but there is no group of marine animals that corresponds to the 

 herbivora and rodents and the plant-eating birds and insects of 

 the land. 



There is so much room in the vast spaces of the ocean, and 

 so much of it is hidden, that it is only when surface animals are 

 gathered together that the abundance of marine life becomes visi- 

 ble and impressive ; but some faint conception of the boundless 

 wealth of the ocean may be gained by observing the quickness 

 with which marine animals become crowded together at the sur- 

 face in favorable weather. On a cruise of more than two weeks 

 along the edge of the Gulf Stream I was surrounded continually 



