Flatworm facts for kids
Quick facts for kids Flatworm |
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| In a clockwise spiral, starting from top left: Eudiplozoon nipponicum (monogeneans), pork tapeworm (tapeworms), common liver fluke (trematodes), Pseudobiceros hancockanus (Turbellaria) | |
Scientific classification  |
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| Kingdom: | Animalia |
| Subkingdom: | Eumetazoa |
| Clade: | ParaHoxozoa |
| Clade: | Bilateria |
| Clade: | Nephrozoa |
| (unranked): | Protostomia |
| (unranked): | Spiralia |
| Clade: | Rouphozoa |
| Phylum: | Platyhelminthes Claus, 1887 |
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Traditional: Phylogenetic:
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| Synonyms | |
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Flatworms (Platyhelminthes, Greek "platy"': flat; "helminth": worm) are a phylum of invertebrates. They are relatively simple animals. They have soft bodies.
With about 25,000 known species, they are the largest phylum of animals without a body cavity. Flatworms can be found in marine, freshwater, and even damp terrestrial environments.
A troublesome terrestrial example is the New Zealand flatworm, Arthurdendyus triangulatus. It is an invasive species which colonized large areas of Ireland and Scotland. It was brought there by accident in the 1960s. Since then, it has destroyed most of the indigenous earthworms.
Most free-living flatworms found in Britain are very small ranging from 5mm to less than 1 cm. They are usually black and can easily be mistaken for debris. These are mostly found in freshwater rivers or streams and are of the Turbellaria class.
Most flatworms (over 50%) are parasitic on other animals. There are four classes:
- Trematoda (Flukes): internal parasites.
- Cestoda (Tapeworms): internal parasites.
- Monogenea: external parasites.
and
- Turbellaria: free-living flatworms, sometimes called 'Planarians'. Planaria is actually a genus.
Flatworms are one of the invertebrate groups which are studied in school biology. The main reason for this is that they may infect humans, pets and farmyard animals, and this was a problem. Some do enormous harm to humans and their livestock. Schistosomiasis, caused by one genus of trematodes, is the second most devastating of all human diseases caused by parasites, surpassed only by malaria. Effective treatments are now available for these infections. Also, in first-world countries, regulations on domestic cattle prevent infected meat from reaching the human hosts.
Adaptations
Flatworms have some incredible adaptations that help them survive. Many have specialized cells called rhabdites that secrete a sticky mucus. This mucus helps them adhere to surfaces and protects them from predators. Some flatworms also have amazing sensory organs, including eyespots that can detect light and dark. These eyespots aren't as sophisticated as our eyes, but they help the flatworms navigate their environment. Many flatworms also have a remarkable ability to regenerate lost body parts. If a flatworm is cut in two, each piece can often regenerate into a complete, new worm! This process has been studied extensively, with scientists discovering many fascinating details about the cellular and molecular mechanisms involved. Research into flatworm regeneration continues to this day, with hopes of applying this knowledge to regenerative medicine in humans.
Interesting facts about flatworms
- Number of species: Over 20,000
- Size: Ranges from a few millimeters to several centimeters
- Habitat: Found in freshwater, saltwater, and damp soil
- Diet: Varies widely, from algae and small invertebrates to the internal tissues of their hosts
- Reproduction: Most flatworms reproduce sexually, but some can also reproduce asexually.
- Lifespan: Varies greatly depending on the species.
- In 2000, an estimated 45 million people were infected with the beef tapeworm Taenia saginata and 3 million with the pork tapeworm Taenia solium.
Other pages
Images for kids
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Various parasitic flatworms from Haeckel's Kunstformen der Natur (1904)
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The turbellarian Pseudoceros dimidiatus
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Life cycle of the digenean Metagonimus
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Magnetic resonance image of a patient with neurocysticercosis demonstrating multiple cysticerci within the brain
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Silhouettes of bodies of various polyopisthocotylean Monogeneans
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Life cycle of the eucestode Taenia: Inset 5 shows the scolex, which has four Taenia solium, a disk with hooks on the end. Inset 6 shows the tapeworm's whole body, in which the scolex is the tiny, round tip in the top left corner, and a mature proglottid has just detached.
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See also
In Spanish: Platyhelminthes para niños
