River darter facts for kids
Quick facts for kids River darter |
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Hadropterus shumardi Girard, 1859 |
The Percina shumardi, also known as the river darter, is a small freshwater fish. It lives at the bottom of rivers and streams, which is called being benthic. This fish is part of a larger group called Percidae, which includes other well-known fish like perch and pikeperch. River darters are originally from North America. They like to live in small and medium-sized rivers where the water is clear, fast-flowing, and has rocky areas. A river darter can grow up to about 7.3 centimeters (almost 3 inches) long and usually lives for about three years. You can tell them apart from other darters by the special spots on their front and back dorsal fins.
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Where Do River Darters Live?
The river darter is found only in the United States and Canada. In Canada, you can find them in southern areas, including the Hudson Bay basin, Ontario, and Manitoba. In the United States, they live in a wide band that stretches from Canada down through Minnesota and North Dakota. They continue all the way to the Gulf of Mexico drainages in Alabama and Texas. The river darter is actually the most common type of darter found in the main channel of the Mississippi River.
What Does a River Darter Look Like?
Darters have two fins on their back, called dorsal fins. They also have a line of special scales along the middle of their body. They have two fins on their underside, called anal fins, and a complete lateral line, which helps them sense movement in the water. River darters have a slightly pointed snout and a mouth that is a bit underneath their head.
These fish are usually olive-brown with distinct dark blotches on their back. These blotches form 8 to 15 faint bars along their body, which become more oval-shaped towards their tail. You can also see a clear bar just below their eye. Their dorsal fins are clear with light bands. During the breeding season, male river darters develop a bright, golden band on the back part of their first spiny dorsal fin. The second dorsal fin has up to 16 soft rays, and the anal fin has 11 rays. Males become darker and their markings stand out more during the spawning season. However, they don't get bright colors like many other darter species. Small bumps called tubercles can grow on the tail, pelvic, and anal fins of males during breeding season. Sometimes, these bumps also appear on their heads.
River Darter Homes: What Kind of Habitat Do They Need?
As their name suggests, river darters live in large rivers and at the mouths of smaller streams that flow into them, called tributaries. They prefer areas with moderate to fast currents, usually in water about 1 meter (3 feet) deep. They like to live in chutes of oxbow rivers and riffles, which are shallow, rocky parts of a stream. These areas often have sandy, gravelly, and rocky bottoms.
In the evening, river darters move closer to the shore. You can often find them along sandbars in shallower water, about 0.6 to 0.9 meters (2 to 3 feet) deep. During the day, they move away from the shore and are most common in water that is 1.2 meters (4 feet) deep or more.
Protecting River Darters
The fact that river darters are common in the Mississippi River and its tributaries shows that they are not super sensitive to cloudy water (turbidity) or water pollution. However, river darters need deep, fast-flowing water habitats. These types of habitats are becoming less common because of flood control projects and river dams. Darters are at risk from pollution because they are small and they breed and feed on the river bottom, which can be greatly changed by pollution. About one-half to one-third of all darter species are currently at risk of disappearing. To protect the river darter, rivers need to be kept as natural as possible, with their normal water flow patterns. The best time to count river darters is in the summer, when water levels are usually at their lowest.
What Do River Darters Eat?
The river darter is an invertivore, meaning it eats invertebrates. They mostly feed during the day. Adult river darters eat many different kinds of aquatic invertebrates. This includes larvae of midges and caddisflyes, which are common in streams and rivers. Snails are also a very important part of the diet for adult river darters. Other key foods for adult darters include chironomids, trichopteras, and small crustaceans. Young river darters, called juveniles, usually eat much smaller prey. Their main food sources are tiny zooplankton that float in the freshwater.
River Darter Life Cycle
River darters grow most of their adult size during their first year. They become ready to reproduce by the time they are one year old. Males tend to grow faster and become larger than females. The average river darter lives for about 3 to 4 years.
River Darter Reproduction
River darters lay their eggs, a process called spawning, from February to May. River darters are "brood hiders," which means they do not guard their eggs. After laying their eggs, they do not provide any parental care. Females bury their fertilized eggs in gravel depressions in areas where the current is slow. These gravel depressions are called redds. River darter eggs can handle temperatures between 13 and 26 degrees Celsius (55 to 79 degrees Fahrenheit). Some reports suggest that river darters swim upstream during the spring to spawn. After spawning, the fish might move downstream to find places to spend the winter. The newly hatched larvae may also drift downstream. As they grow, the young darters move into the faster water habitats that adult darters prefer.
Why Is It Called a River Darter?
The scientific name for the river darter, Percina shumardi, has two parts. Percina comes from a Greek word that means 'little perch'. The second part, shumardi, was given to honor Dr. George C. Shumard (1823-1867). He was a surgeon who discovered the fish while working on the United States Pacific Railroad Survey.
