Handbook of Nature-Study · Lesson XLIII · Topic 3: Fish study
43. The johnny darter
Goal: Your child can describe how the johnny darter rests and "walks" on the stream bottom with its fins and darts away when frightened.
You'll need
- A shallow, clear, gravelly stream with a gentle riffle
- A small net and a white dishpan or clear container
- Water shoes (for an adult)
- Nature notebook
What's in the book
The leading thought, the method (catch them with other small fry; they do best in running water) and eight questions about its shape and the W-shaped marks on its side, how its paired fins are used, its two dorsal fins, how it rests, walks and climbs, how it darts, its tail, its eyes, and where it lives. Quotations from L. H. Bailey on the brook as the best of all nature-study subjects close the fish section.
The lesson, step by step
When and where
Late spring through early fall, in clear, shallow streams with sandy or gravelly bottoms. Look closely at the bottom in calm water near a riffle; johnny darters are small, sandy-brown and sit very still. Safety: an adult stays within arm's reach near any water. Stay off steep or slippery banks and never wade in fast water.
Keep the big idea in mind
Read this to yourself:
The johnny darter naturally rests upon the bottom of the stream where the current is swift. It uses its two pairs of paired fins somewhat as feet in a way interesting to observe.
Find one
Stand still in the shallows (adult) or on a rock and watch the bottom until something tiny darts and stops.
Where do we find the johnny darters? In what part of the stream do they live? Are they usually near the surface of the water or at the bottom?
A close look
If you catch a fish to look at, use a small net, keep it in a clear container of water from the same stream, in the shade, for no more than 10 to 15 minutes, then let it go exactly where you caught it. Wet your hands before touching a fish, or better, don't touch it at all. Check your state's rules first; some places need a fishing license even to net small fish.
Can you see the W-shaped marks along its side? How is it colored above?
Fins as feet
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?
When resting on the bottom how are the pectoral fins used?
Darting
When frightened how does it act? Why is it called a darter?
What is there peculiar about the eyes of the johnny? Describe the eyes and their position. What reason is there in the life of the fish that makes this position of the eyes advantageous?
Let it go and tell back
Return the darter to the same spot. Ask your child why a fish that lives in fast water might rest on the bottom. Then share the leading thought.
Nature notebook
Draw a johnny darter propped on its fins on a pebble, with its W marks. Copy one line from the Bailey quotation on the page: "To my mind, the best of all subjects for nature-study is a brook."
Afterwards
Spend one more session just sitting by the brook, as Bailey suggests, and list every living thing you see in fifteen minutes.
Tip
Turning over stream rocks hurts the homes of many small creatures. If you lift one, put it back exactly as it was.