ZOOLOGY. 



of much moment to the fishermen. The food of fishes is very 

 diverse. Some forms are actively carnivorous, preying on 

 animals as large or larger than themselves (sharks) ; others, 

 and these are the most numerous class, depend upon small 

 animals such as the young of their own or other species of fish, 

 on Crustacea, insects and worms. The microscopic animals and 

 plants occurring in immense numbers in the water are im- 

 portant items in the food of fishes. Some fishes are scaven- 

 gers, living largely upon the dead materials found in the water. 

 Fishes differ much in their energy, courage, and resistance to 

 attack. Those possessing these qualities in high degree are 

 denominated " game " fish and are prized for the difficulty 

 involved in their capture. The family of the trout and salmon 

 includes several such species. 



381. Economic Value. From primitive times fish has been 

 one of the important human foods. Probably a larger per- 

 centage of the well-known species of fishes are regarded as 



FIG. 1 80. 



FIG. 180. Atlantic Salmon (Salmo salar). From the " Manual of Fish Culture," 



U. S. F. C. 



Questions on the figure. What are the names of the various fins 

 shown in the figure? What is the dotted line along the side of the fish? 

 What type of tail has this fish? 



edible than of any other animal group. Their rate of multi- 

 plying and their occurrence in schools at available points are 

 quite as important factors as the delicacy of the flesh in de- 



