CHARACTERISTICS AND HABITS OF FISHES 31 



With a few notable exceptions, the various species of 

 demersal fish feed upon smaller fish. Thus 



The hake, normally a deep-water fish, ventures inshore 

 in pursuit of herrings, pilchards, mackerel. 



The ling, turbot, brill, dog fish live entirely upon small 

 fish. The dog fish swarms on certain fishing grounds 

 and is often a serious pest to the drift-net fishermen, 

 destroying their nets as well as the fish that are 

 attached to them. 



The whiting, like the cod, feeds upon small fish, and 

 upon Crustacea and mollusca. 



The food of the haddock consists of mollusca, Crustacea 

 and marine worms, etc. 



The sole lives on small Crustacea, for example shrimps, 

 and marine worms. 



Skates and rays feed upon mollusca and Crustacea. 



Most shellfish live in shallow water and feed upon the 

 plankton. 



The methods by which fish obtain their food differ 

 greatly according to the species of the fish. Pelagic 

 fish, e.g. herring and mackerel, sprat and pilchard, 

 obtain their food almost automatically as they swim 

 open-mouthed through the water in which it abounds. 

 These direct plankton-feeders possess comb-like struc- 

 tures the gill-rakers attached behind the gill openings, 

 and as the food-bearing water streams through the mouth 

 and gill openings of the fish, these structures strain the 

 food from it. The fish licks the plankton from its 

 gill-rakers with its tongue and swallows it. 



Many pelagic fish, e.g. carp, trout, salmon, look for 

 their food while swimming through the well-lighted 

 surface water. 



Demersal fish flat fish, cod, haddock, etc. seek their 

 food by scent and touch. The cod possesses a barbel at- 

 tached to its chin, by means of which it feels for its food. 



