Symsagittifera roscoffensis

Teased by Lynn Margulis' book Symbiotic Planet[Error: Wrong macro arguments: "228 page=\"9\"" for macro 'ref' (maybe wrong macro tag syntax?)] , I visited Roscoff this summer to see the the flatworm Symsagittifera roscoffensis, formerly Convoluta roscoffensis and take some photos and videos.

Roscoff is a picturesque little harbor in Brittany. It hosts a station of marine biology.But what fascinated me most was not so much good food and impressive music performed in the church, but that little flatworm that lives in puddles along the shore and hosts a lot of unicellular green algae.

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During low tide at Roscoff's sandy beaches ...

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puddles can be found that look as if some green algrae did not make it to the waters.

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But a closer look reveals that these 'algae' consist of many small individuals that are rapidly moving and quickly disappear.

To catch these 'algae' that are actually flatworms, a shell so abundantly found at the shore can be used.

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First one has to scoop up some of the 'green sand'.

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Instantly the green flatworms will disappear from the sand and the shell looks empty with only sand in it.

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Finally the sand can be thrown out and the flatworms that stick to the wall quickly move down the gravity into the remaining water.

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Here they can be observed with all their beauty ...

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and their gracious movements followed.

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The last two videos show two experiments that a shaking ground can cause the worms to escape into the sand.
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