About Flatworms

Phyla

  • Flatworms: The First Hunter

Animation

  • Flatworm Animation: Body Plan
  • Flatworm Animation: Tapeworm
  • Flatworm Animation: Reproduction

Behavior

  • Flatworms: Reproduction
  • Flatworms: An Invasive Flatworm Hunts Earthworms

Videos

 

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Planaria illustrates bilateral symmetry.

 

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A predatory flatworm hunts a snail, on land

 

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Flatworm swimming

 

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A flatworm lifting off from a coral reef and swimming

 

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A song, with video about flatworms

Reading

GETTING A HEAD The First Hunter

Excerpt from the Shape of Life book.

 

GENERAL INFORMATION ABOUT FLATWORMS

FEATURED CREATURE

The Crazy World of Penis Fencing

The Badass New Guinea flatworm, Platydemus manokwari

 

ORIGINS

Researchers say tiny marine worms called acoels may be one of the closest living representatives of the first bilaterally symmetrical organisms. Using DNA analyses, the team concludes not only that the acoels don't belong with other flatworms, but that they alone represent a living relic of the transition between radially symmetrical animals such as jellyfish and more complex bilateral organisms such as vertebrates and arthropods. From a Flatworm, New Clues on Animal Origins.

Scientists found fossil tracks of the earliest bilateral animal from at least 585 million years ago. The tracks they found indicated a front and back as well as a top and bottom. Fossil of Early Bilateral Animal.

Researchers at the University of California, Davis, discovered a bi-lateral worm-like fossil from before the Cambrian Explosion. This suggests that a bilateral body plan may have evolved earlier than previously thought, read more.

 

FLATWORMS AMAZING ABILITIES

Some flatworms use the mitochondria in some cells (which we all have) in their heads to form lenses to focus light onto their light sensitive cells. Read the article on Creature Cast.

Planarians can regenerate body parts including growing a new head and brain. When scientists studied the process identified the gene that makes this possible and that the planarians have stem cells to make these new body parts. Read more.

Scientists are investigating how planarians maintain the stem cells that let them regenerate.  Learn more.

 

ROLE IN ECOSYSTEM

Invasive flatworms can cause major disruptions to ecosystems: read about an invasive flatworm on the Shape of Life website.

Researchers at the University of New Hampshire found that flatworms in estuaries can indicate the health of the ecosystem.

Flatworms play a role in many food chains. Read about some of them.

Parasitic flatworms can disrupt ecosystems. Learn more.

 

HUMAN USE

Some flatworms, planaria, can be used as models for toxicology (2015). Read an article from UC San Diego: "Flatworms Could Replace Mammals for Some Toxicology Tests".

 

PHOTO RESOURCES

Platyhelminthes from the Florida Museum of Natural History.

The Marine Flatworm Galleries.

General Info

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    Book with pencil

Role in Ecosystem

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    Bee with arrows around it

Climate

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    Thermometer and waves

Human Interaction

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    Human next to globe

Paleontology

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    Skull of dinosaur
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    Red orange and pink flatworm
    Factsheet
    Flatworms: An Ancient Body Plan
    Around 20,000 flatworm species today have the same basic body plan that appeared roughly 500 million years ago.

    Download Factsheet

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    Black and yellow flatworm
    Reading
    Flatworms: Getting Ahead, An Explosion of Life
    When you collect marine animals, there are certain flatworms so delicate that they are almost impossible to capture whole, for they break and tatter under the touch. You must let them ooze and crawl of their own will onto a knife blade and then lift them gently into your bottle of seawater.

    Download Reading