

PISCES 237 



vegetation; suckers have their mouths turned, downward 

 for feeding from the bottom. Perch are equally at home in 

 the depths of lakes or in the dense growth of plants along- 

 shore; also thrive in ponds and streams. They can feed 

 from the surface, strain microorganisms from the open 

 water, snatch snails and the larvae of insects from their 

 retreats among plants or stones, and grub about in the soft 

 bottom mud for minute worms and insect larvae. 



In its sensory equipment for finding food a perch presents 

 a rather generalized condition when compared with many 

 other fresh-water fishes. A bullhead, for example, pays 

 little attention to moving objects unless they touch it, but 

 seeks food by swimming so that the body swings from side 

 to side. The "whiskers, " or barbels, which bear taste 

 organs, thus encounter a considerable part of the area being 

 explored. If a barbel touches something that is suitable 

 for food, the fish at once turns and snaps up the morsel. A 

 trout, on the contrary, depends little on its senses of taste 

 and smell in seeking food, but is quick to investigate any 

 small moving object. It chases bubbles, pursues floating 

 twigs, and examines everything that moves in its imme- 

 diate vicinity, thus capturing many small insects and other 

 organisms. The bullhead in hunting depends primarily on 

 its senses of taste and smell, the trout uses its sense of sight 

 more than any other. The perch, however, has enough 

 versatility to feed in various ways and therefore has greater 

 opportunities for securing food. Its acute eyes enable it to 

 feed on the small moving things sought by the trout; its 

 sense of taste, though not distributed so widely in the skin as 

 that of the bullhead, is still good enough to be of value in 

 locating and judging the value of food. The presence of 

 food substances may also be known through dilute solutions 

 given off in the water which are perceived by the sense of 

 smell. If anything moves that promises food it is investi- 

 gated and perhaps even taken into the mouth, to be rejected 

 again if not suitable. If there is a flavor of snail, or .worm, 

 or insect in the water, it is followed to its source. Small 



