Flatworm facts for kids

Flatworms (also called Platyhelminthes) are a group of simple animals that do not have a backbone. Their bodies are soft and flat, like a ribbon or a leaf. The name "Platyhelminthes" comes from Greek words meaning "flat" and "worm."

There are about 25,000 different kinds of flatworms known today. They are the biggest group of animals that do not have an internal body cavity. You can find flatworms almost everywhere! They live in the ocean, in freshwater rivers and lakes, and even in damp places on land.

One example of a land flatworm is the New Zealand flatworm. It accidentally came to places like Ireland and Scotland in the 1960s. This flatworm caused problems because it ate many of the native earthworms there.

Most free-living flatworms in places like Britain are very small. They are usually less than 1 centimeter long and often look black. People sometimes mistake them for dirt! These tiny flatworms often live in freshwater rivers or streams.

Most flatworms (more than half of all species!) are parasites. This means they live inside or on other animals and get their food from them. There are four main groups, or classes, of flatworms:

• Trematoda (Flukes): These are parasites that live inside other animals.
• Cestoda (Tapeworms): These are also parasites that live inside other animals.
• Monogenea: These flatworms are parasites that live on the outside of other animals.
• Turbellaria: These are free-living flatworms, meaning they do not live as parasites. They are sometimes called 'Planarians'.

Flatworms are often studied in school science classes. This is partly because some types can infect humans, pets, and farm animals. While some can cause serious health problems, doctors now have good ways to treat these infections. Also, in many countries, rules about meat safety help prevent infected food from reaching people.

Amazing Adaptations

Flatworms have some really cool ways to survive. Many of them have special cells called rhabdites. These cells make a sticky slime, or mucus. This mucus helps the flatworms stick to surfaces and protects them from animals that might try to eat them.

Some flatworms also have amazing sense organs. They have simple eyespots that can tell the difference between light and dark. These eyespots are not like our eyes, but they help the flatworms find their way around.

Many flatworms have an incredible ability to grow back lost body parts. If a flatworm is cut into two pieces, each piece can often grow into a whole new worm! Scientists have studied this process a lot. They hope to learn how this works so they can use that knowledge to help humans with medical treatments in the future.

Cool Facts About Flatworms

• There are over 20,000 different kinds of flatworms.
• They can be tiny, just a few millimeters long, or quite large, several centimeters long.
• You can find them in freshwater, saltwater, and damp soil.
• Their diet is very different depending on the type. Some eat algae or small bugs, while parasites eat parts of their hosts.
• Most flatworms reproduce by having a male and female part, but some can also make copies of themselves without a partner.
• Their lifespan changes a lot depending on the species.
• In the year 2000, about 45 million people were infected with the beef tapeworm and 3 million with the pork tapeworm.

Want to Learn More?

• List of animal phyla
• Fasciola hepatica
• Planaria

Images for kids

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  Different kinds of parasitic flatworms from a book called Kunstformen der Natur (1904)

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  The free-living flatworm Pseudoceros dimidiatus

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  Life cycle of the flatworm Metagonimus

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  A brain scan showing small cysts caused by a tapeworm infection

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  Silhouettes of different kinds of Monogenea flatworms

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  The life cycle of the tapeworm Taenia: Inset 5 shows the head, which has four suckers and hooks. Inset 6 shows the whole body of the tapeworm.

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See also

In Spanish: Platyhelminthes para niños