170 NATURE-STUDY 



about the use of these. Any boy who has been fishing can 

 tell of his experience with them. 



Most fish are covered with scales that overlap each other 

 and make a protective armor. Examine some separate 

 scales from different kinds of fish. The outside of the body 

 is covered with a slimy substance which protects the body 

 and also enables the fish to elude the grasp of its enemies. 

 The scales are often beautifully colored. Our common 

 " pumpkin seed" sunfish displays a wonderful wealth of 

 color and beautiful iridescence. Most fishes, however, 

 are inconspicuously colored for protection. Brown and 

 olive colors are common on the backs of many fishes. 

 This renders them inconspicuous against the darker depths 

 of the water or the bottom. Underneath, however, fishes 

 are generally lighter colored, often nearly white. This makes 

 them less easily seen against the bright upper surface of the 

 water. Some strange fish of the ocean have curious warty 

 and spiny surfaces and long streamers, so that they more 

 effectively resemble water vegetation. 



The eyes of fishes are lidless, and are usually large and 

 staring. Their mouths differ much in shape and in position, 

 and those of predaceous kinds are large and well supplied 

 with teeth. Bottom feeders have 'their mouths more on the 

 under side of the head. 



Observe the fish in the aquarium. See how it seems to be 

 swallowing all the time. It does take in water, but not to 

 drink, for it forces it out through the openings at the sides 

 just back of the head. These openings lead to the gill 

 pouches and are closed by the cartilaginous gill covers. 

 Take a dead fish and examine the gills. A large fish shows 

 them better. Turn back or cut off the gill cover, and the red 



