Black ghost knifefish facts for kids
Quick facts for kids Black ghost knifefish |
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The black ghost knifefish (Apteronotus albifrons) is a cool tropical fish. It belongs to the ghost knifefish family. These fish come from freshwater rivers in South America. You can find them from Venezuela all the way down to the Paraguay–Paraná River. This includes the huge Amazon Basin. Many people like to keep them in aquariums.
This fish is completely black. It has two white rings on its tail. It also has a white mark on its nose. Sometimes this mark goes down its back like a stripe. It moves around by wiggling a long fin on its belly. It can grow up to 50 centimeters (about 20 inches) long.
Black ghost knifefish are active at night. They are a special kind of electric fish. They use an electric organ and sensors on their body. This helps them find insect larvae in the dark.
The black ghost knifefish lives in fast-moving creeks. These creeks have sandy bottoms. They are found in tropical areas. People in South America have a belief about these fish. They think that the spirits of people who have passed away live inside these fish. That's why they are called "ghost" knifefish.
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How Black Ghost Knifefish Use Electricity
The black ghost knifefish is a special electric fish. It has systems to make and sense electricity. Some fish can only feel electric signals. But the black ghost knifefish can both make and feel them.
Making Electric Signals
The fish makes electric signals using a special organ. This organ is in its tail. These signals are called electric organ discharges (EODs). The fish also has special cells in its skin. These cells are called electroreceptor organs. They help the fish feel changes in electricity.
How They Use EODs
Black ghost knifefish use their EODs for two main things. They use them to find objects around them. This is called electrolocation. They also use them to talk to other fish. This is called communication.
Finding Objects (Electrolocation)
Black ghost knifefish are "wave-type" electric fish. This means they make EODs all the time. They send out a steady stream of electric signals. By feeling how these signals change, they can tell if objects are nearby. This is like using sonar, but with electricity. This is called active electrolocation.
They also have another way to sense electricity. They can feel electric fields made by other things. This is called passive electrolocation. They use different sensors for this. Black ghost knifefish are active at night. They use their electric sense to move around in the dark. It also helps them find their food. They can also feel water movements.
Talking to Each Other (Communication)
Every type of electric fish has its own EOD frequency. This frequency can change based on the fish's age or sex. It also changes when other fish are nearby. These changes in frequency are like different voices. They help the fish communicate.
Black ghost knifefish have learned to avoid "jamming" each other's signals. This means they change their EOD frequency. This stops their signals from getting mixed up. It helps them understand each other better.
Studies have shown that male and female fish have different EOD frequencies. Females usually have a higher frequency. This helps them recognize each other's gender. Also, a fish that is less dominant might change its EOD frequency. This can be a sign that it is being submissive.
You can even hear these fish "talk"! Some museums have special devices. These devices turn the fish's electric signals into sounds. The Bakken Museum in Minneapolis has one of these displays. You can listen to the black ghost knifefish there.
See also
In Spanish: Apteronotus albifrons para niños
