Fun Flatworms Facts For Kids

Divya Raghav
Jan 11, 2023 By Divya Raghav
Originally Published on Aug 05, 2021
Edited by Isobel Murphy
Fact-checked by Spandana Kantam
Find the best flatworms facts about these worms that belong to the Animalia kingdom.
Age: 3-18
Read time: 5.5 Min

If your child gets excited talking or reading about different animal species, this is the right place for them to learn about the amazing organisms called flatworms. While a few of these soft-bodied invertebrates are free-living, most of them (approximately 80%) are parasitic in nature. Flatworms are known to be primitive organisms that were the first organisms to develop a mesoderm. They can survive in any kind of environment with high enough moisture content, but flatworms can be harmful to humans due to their nature. As much as we already know about them, it is an accepted fact that there are still hundreds of flatworm species that are yet to be discovered!

Here are lots of flatworms interesting facts that everyone will enjoy. Let's look at these interesting facts, and if you do like these, then do read about the pygmy slow loris and squirrel monkeys too.

Flatworms Interesting Facts

What type of animal is a flatworm?

Flatworms are soft-bodied invertebrates, belong to the phylum Platyhelminthes. While 80% of them are parasitic in nature, some of them are free-living as well.

What class of animal does a flatworm belong to?

Flatworms from the phylum Platyhelminthes belong to multiple classes: Turbellaria, Monogenea, Trematoda, and Cestoidea.

How many flatworms are there in the world?

Presently, there are approximately 20,000 species of flatworms (inclusive of freshwater planarians and the colorfully patterned marine flatworms).

Where does a flatworm live?

A flatworm's habitat has a wide range. There are freshwater flatworms, worms in ponds, lakes, streams, and debris, and they can also live in their hosts as well. Their host can be humans or different animals.

What is a flatworm's habitat?

Flatworms are found in abundance in countries like New Zealand, Central and South America, islands of the South Pacific, Madagascar, and Australia.

Who do flatworms live with?

These Platyhelminthes usually form a monophyletic group.

How long does a flatworm live?

The life cycle of this worm is not definite. However, some species are known to have lived for between 65 to 140 days.

How do they reproduce?

Most flatworms are known to be hermaphroditic, which means that they have both male and female reproductive organs. However, the mode of flatworms' reproduction varies from species to species. While some species use sexual reproduction (this involves flatworms mating sexually), others use the asexual mode of reproduction. The most common asexual form of reproduction that can be seen among flatworms is fragmentation and budding. Fragmentation happens when the flatworm splits itself into two or more parts, and each part then grows separately and individually. Budding, on the other hand, is an extension of a flatworm that grows on to become a whole new separate flatworm.

In sexual reproduction, flatworms can either produce and fertilize their own eggs (since they are hermaphroditic) or mate with fellow flatworms (their skin absorbs sperms so minimal physical contact is required). After mating, the cocoon is released into the environment, which later develops with time and then hatches.

What is their conservation status?

Flatworms are classified as Not Extinct, this includes many species of flatworms, like roundworms, annelid, and cnidaria.

Fun Facts About Flatworms

What do flatworms look like?

A flatworm has bilateral symmetry and is a cylindrical organism with a hard head and tail. They usually have a brown skin coating accompanied by white dots and are parasitic in nature. They lack a centralized nervous system and hard skeleton and are not harmful in nature. They are a worm shape, but they are extremely flat worms, hence their name!

flatworms are parasitic in nature

How cute are they?

These animals are not that cute at all. In fact, their slimy body makes them look kind of gross!

How do they communicate?

Although flatworms have sensory cell layers on either side of their head, unlike many other animals, they cannot see like us. These parasites only respond to alterations in light. The two nerve cords running down their bodies help them respond to stimuli and trigger their muscles to react.

How big is a flatworm?

A flatworm is tiny in size, at just 0.04-0.4 in (1-10 mm) long.

How fast can flatworms move?

It is hard for these parasites to move fast as their movement depends on the ciliary beat inside their body. They have a dense coat of cilia ranging from head to tail and any ciliary activity leads to the secretion of mucus which helps them glide over surfaces, helping them move. However, these ciliary forces are not strong enough to make large flatworms move and moving flatworms only travel at very slow speeds.

How much does a flatworm weigh?

A flatworm weighs 1.7-3.3 lb (8-15 mg).

What are their male and female names of the species?

There is no specific division of gender among flatworms as they tend to possess both the male as well as female reproductive organs, making them a hermaphrodite species.

What would you call a baby flatworm?

Whilst there is no specific name for baby flatworms, in general, flatworms are also called platyhelminth.

What do they eat?

Flatworms usually feed on tunicates, small crustaceans, worms, and mollusks.

Are they dangerous?

They can carry a parasite called the rat lungworm which can cause meningitis in humans. In addition to this, flatworms produce toxic secretions that might also trigger a severe allergic reaction, so yes there can be dangerous.

Would they make a good pet?

No, a flatworm lives in a host like a worm, lays eggs, and breeds. They are not kept as pets, but humans can become flatworm hosts, often unknowingly. Not only in humans, but you can also find flatworms in dogs and flatworms in cats too.

Did you know...

Flatworms got their name because of their appearance (they are very flat). The reason behind this flat body structure is the absence of a cavity. This absence makes their bodies very flat. They also breathe through the process of diffusion, so their flat body shape ensures that each cell of the body is close enough to the outer surface of the body, ensuring proper oxygen supply to all cells.


Flatworms tend to carry a parasite called the rat lungworm, which can cause meningitis and can be harmful to humans. Tapeworms are one kind of flatworm that can use humans as their host, you can get tapeworms by eating uncooked meat or by drinking contaminated water.

Why are flatworms important to humans?

Approximately 20,000 species of flatworms are known to be living, be it marine flatworms in salt or fresh waters, or flatworms on the land. There are various types of flatworms namely planaria flatworms, parasitic flatworms, freshwater flatworms, saltwater flatworms, and New Guinea flatworms. The presence of these invertebrates can be valuable to humans as they tend to increase the quality of successful organic farming and they may also regulate the population of zooplankton in water bodies. Their consumption of algae is also useful as it limits levels of algae in water bodies too.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other arthropods including the giant African millipede, or the Atlas beetle.

You can even occupy yourself at home by drawing one on our flatworms coloring pages.

Flatworms Facts

What Did They Prey On?

Crustaceans, worms, tunicates, and mollusks

What Type of Animal were they?


Average Litter Size?


How Much Did They Weigh?

1.7-3.3 lb (8-15 mg)

What habitat Do they Live In?

puddles, ponds, lakes, under rocks and debris, or around freshwater

Where Do They Live?

new zealand, central, South America , islands of the south pacific, madagascar, and australia

How Long Were They?

0.04-0.4 in (1-10 mm)

How Tall Were They?



Turbellaria, Monogenea, Trematoda, and Cestoidea





Scientific Name


What Do They Look Like?

Brown, black, or a red hue with white dots

Skin Type

Soft body

What Are Their Main Threats?

the six-line wrasse, yellow wrasse, and the spotted mandarin

What is their Conservation Status?

Least Concern
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Written by Divya Raghav

Bachelor of Commerce specializing in Accounting and Finance, Master of Business Administration

Divya Raghav picture

Divya RaghavBachelor of Commerce specializing in Accounting and Finance, Master of Business Administration

With a diverse range of experience in finance, administration, and operations, Divya is a diligent worker known for her attention to detail. Born and raised in Bangalore, she completed her Bachelor's in Commerce from Christ University and is now pursuing an MBA at Narsee Monjee Institute of Management Studies, Bangalore. Along with her professional pursuits, Divya has a passion for baking, dancing, and writing content. She is also an avid animal lover who dedicates her time to volunteering for animal welfare causes.

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