ORIGIN OF THE FOOD OF MARINE ANIMALS. 89 



small animals which live among the plants. All the floating fishes whose home is the 

 floating sargassum — the file-fishes and trigger-fishes (Ballistida), the trunk-fishes 

 (Ostracion), the frog-fishes (Ante una ri us), and the puffing-fishes (Tetradon and Dio- 

 don) — are carnivorous, living upon the barnacles and mollusks and hydroids which 

 grow upon the sargassum, or upon the Crustacea, young fishes, and the floating larvae 

 which seek its shelter. 



In the Chesapeake Bay the sheepshead (Archosargus probatocephalus) 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 crush the 

 barnacles andyouug oysters until the juices 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. 



The vast majority of marine fishes are fierce hunters, pursuing and destroying 

 smaller fishes, and often exhibiting an insatiable love of slaughter, as in the case of 

 our own bluefish and the tropical albacore and barracuda. Others, such as the her- 

 ring, 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 microorganisms, and others which hunt and destroy each other; but there 

 is no group of marine animals which corresponds to the herbivora and rodents and 

 plant-eating birds and insects of the land. The pelagic copepods are, of all the 

 marine metazoa, the ones whose place in the economy of nature is most like that of 

 the terrestrial plaut-eaters. They swarm in innumerable multitudes at the surface of 

 the ocean, and also below it down to a depth of a mile or more, and they furnish the 

 chief food for most young fishes, and for great armies of herrings and pteropods and 

 jelly-fishes and siphonophores, and for most pelagic larvos. 



There are plant-eating mollusks and echinoderms and annelids in the ocean, but 

 not in sufficient numbers to play any conspicuous part in its economy, and the cope- 

 pods are the only plant-eaters which exist in sufficient numbers to be compared with 

 those of the laud, and the food of the copepods is only partially vegetable, for they 

 devour microscopic animals as well as microscopic plants, and probably to an equal 

 amount. 



The group Crustacea as a whole is a carnivorous one, however, for while a few 

 subsist on algos, their number is inconsiderable. Others chew the mud of the bottom 

 and extract its organic matter, but this is chiefly animal and consists of foraminifera 

 and rhizopods and infusoria. 



The mollusks as a whole are carnivorous, and while there are many exceptions, 

 such as the nudibranchs, for example, many nudibranchs feed on hydroids. 



The cephalopods and pteropods and heteropods and many of the gasteropods 

 pursue and destroy their prey, and other gasteropods are scavengers, while the 

 lamellibranchs gather up the microscopic organisms which are drawn into their gills 

 with the water. 



The majority of the worms and echinoderms are animal-feeders. Some of them, 

 like the common starfish, are actively predaceous; others, like the crinoids, gather 



