Fish Study 179 



The tail and the dorsal fin of the johnny darter are marked with silver 

 dots which give them an exquisite spun-glass look ; they are as transparent 



as gauze. 



The johnny darters live in clear, swift streams where they rest on the 

 bottom, with the head up stream. Dr. Jordan has said they can climb 

 up water weed with their paired fins. I have never observed them doing 

 this but I have often seen one walk around the aquarium on his fins as if 

 they were little fan-shaped feet; and when swimming he uses his fins as a 

 bird uses its wings. There are many species of darters, some of them the 

 most brilliantly colored of any of our fresh-water fishes. The darters are 

 perch-like in form. 



Dr. Jordan says of the breeding habits of the darters: "On the bot- 

 tom, among the stones, the female casts her spawn. Neither she nor the 

 male pays any further attention to it, but in the breeding season the male 

 is painted in colors as beautiful as those of the wood warblers. When you 

 go to the brook in the spring you will find him there, and if you ctach him 

 and turn him over on his side you will see the colors that he shows to his 

 mate, and which observation shows are most useful in frightening away 

 his younger rivals. But do not hurt him. Put him back in the brook 

 and let him paint its bottom with colors of a rainbow, a sunset or a gar- 

 den of roses. All that can be done with blue, crimson and green pig- 

 ments, in fish ornamentation, you will find in some brook in which the 

 darters live." 



LESSON XLII 



JOHNNY DARTER 



Leading thought The johnny darter naturally rests upon the bottom 

 of the stream where the current is swift. It uses its two pair of paired 

 fins somewhat as feet in a way interesting to observe. 



Method Johnny darters may be caught in nets with other small fry 

 and placed in the aquarium. Place one or two of them in individual 

 aquaria where the pupils may observe them at their leisure. They do 

 best in running water. 



Observations i. Describe or sketch the johnny darter from above. 

 From the side. Can you see the W-shaped marks along its side? How is 

 it colored above? 



2. How are the pectoral fins placed? Are they large or small? 

 How are they used in swimming? Where are the ventral fins placed? 

 How are the ventrals and dorsals used together? When resting on the 

 bottom how are the pectoral fins used? 



3. What is there peculiar about the dorsal fins of the johnny 

 darter? When he is resting, what is the attitude of the dorsal fins? 

 What is the difference in shape of the rays of the front and hind dorsal 

 fins? 



4. When resting on the bottom of the aquarium how is the body 

 held? On what does it rest? In moving about the bottom slowly why 

 does it seem to walk? How does he climb up water weed? 



^ 5. When frightened how does it act? Why is it called a darter? 

 What is the attitude of all the fins when the fish is moving swiftly? 

 6. What is the shaoe of the tail? 



