Harlequin darter facts for kids
Quick facts for kids Harlequin darter |
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The harlequin darter (Etheostoma histrio) is a small, colorful fish. It belongs to a group of fish called darters. Darters are part of the perch family, which also includes fish like perches and pike-perches. This special fish lives only in the eastern half of the United States.
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What Does the Harlequin Darter Look Like?
The harlequin darter is a small fish. It usually grows to about 5.3 centimeters (2 inches) long. Some can reach up to 7.7 centimeters (3 inches).
Its sides are green. It has six or seven brown saddle-like markings on its back. The belly is usually yellow or tan with dark spots. The base of its tail fin often has a B shape.
The first fin on its back is clear with a red edge. Its other fins are mostly dark with many dark spots. Males and females look alike most of the time. However, during breeding season, males turn a much brighter green. The name "harlequin" comes from the mask-like markings on its face. These include a dark bar below its eye and dark spots on its head and chest.
Where Do Harlequin Darters Live?
Harlequin darters were first found in the Ouachita River in Arkansas. They were also found in the Poteau River in Oklahoma. Now we know they live across much of the southeastern United States. They are found in rivers that flow into the lower Mississippi River.
You can find them from Illinois down to Florida and as far west as Texas. Most live south of the Fall Line. This is a line on a map where harder, older rocks meet softer, younger rocks. The northernmost harlequin darter was found in the Embarras River in Illinois.
In Tennessee, they only live in the western part of the state. They are in the Mississippi River and its western tributaries. Scientists think we might not know their full range. This is because they like to live in places that are hard to study.
They prefer areas with lots of woody debris in large, fast-moving rivers. Special methods are needed to find them. This can lead to mistakes in counting them.
Harlequin darters were once on Indiana's endangered species list. But then more populations were found. Their numbers are growing in the Wabash River area of Indiana. In Florida, they are only found in one river system, the Escambia. This makes them very vulnerable to big problems in that area. Dams built in Alabama have also cut them off from other groups of darters. Harlequin darters are spread out, but they are not very common anywhere.
What Do Harlequin Darters Eat?
Harlequin darters eat small creatures that live on the river bottom. These include larvae (young forms) of midges, caddisflies, mayflies, and blackflies. Darters are very diverse because they are good at living in specific places.
This darter likes fast-flowing parts of rivers called riffles. These areas usually have good water quality. What makes them special is that they depend on dead leaves and branches. These are called detritus and downed woody debris.
They are one of the few darter species found in the main part of the Mississippi River. They often avoid smaller streams. Farm runoff can flow into these large rivers. This increases levels of nitrates and phosphates. These chemicals can make the water unhealthy for darters. Also, companies sometimes remove plants and woody debris near rivers. This hurts the harlequin darter's home even more.
Harlequin Darter Life Cycle
Harlequin darters lay their eggs once a year, in February or March. The female looks for a good place to lay eggs, and the male follows her. Sunken logs or branches are often perfect nesting spots for them.
When the female lays her eggs, they stick to the detritus in deep water at the nesting site. Female darters can start having babies when they are one year old. A female can lay anywhere from 90 to 450 eggs. The number of eggs depends on her age. Harlequin darters can live for up to four years.
These fish are thought to move around a lot during different seasons. From late spring to fall, they usually stay in smaller streams. During colder months, they move into larger reservoirs and big rivers. After laying eggs, adult darters seem to move away from large rivers. They go into smaller streams. They leave the young fish from that year in the big rivers and reservoirs.
Scientists found that in places where adults were caught in winter, only young darters were caught the next May. This suggests that dams and other things that block movement can harm their life cycle. Removing woody debris from their spawning areas also hurts them.
Protecting Harlequin Darters
Right now, there isn't much effort to protect harlequin darters in most places. It's hard to count them, so we don't have much information about their numbers. The harlequin darter is not considered an endangered or threatened species by the U.S. government.
Only a few states have plans to protect this fish. The Missouri Department of Conservation is one of them. They have rules to help the harlequin darter. For example, they limit when work can be done near wetlands to protect breeding darters. They also leave plants and woody debris in the water. They use fences to stop dirt from washing into streams. They avoid building permanent dams that block fish movement. They also try to avoid crossing streams where darters live.
A study in Florida found similar problems. Removing woody debris, building dams, and dirty water hurt harlequin darter numbers. The study also said that oil and coal exploration could be a threat. However, Florida does not have a direct plan to protect its harlequin darter population. This is important because the harlequin darter is a "species of special concern" in Florida.
How Can We Help Harlequin Darters?
Harlequin darters move between big rivers and smaller streams during the year. So, removing dams and other things that block their path would help them. These fish also rely a lot on woody debris and other natural materials. They prefer these over sandy river bottoms.
To help them, we should limit removing plants and woody debris in and around their habitats. Also, because they live in places that are hard to study, we need to try harder to count them. This will help us know their true numbers.
Pollution from farms can also hurt these fish. Using good farming practices and keeping natural areas along stream banks can help. This would make the water healthier for darters and other water animals. Using silt fences around construction sites can stop dirt from washing into the water. Also, encouraging landowners to join programs that protect land can help. These programs can reduce soil erosion and improve water quality. This also helps people by improving groundwater and reducing flood damage.
