Symsagittifera roscoffensis
Symsagittifera roscoffensis | ||||||||||||
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Numerous specimens of Symsagittifera roscoffensis |
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Systematics | ||||||||||||
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Scientific name | ||||||||||||
Symsagittifera roscoffensis | ||||||||||||
( Graff , 1891) |
Symsagittifera roscoffensis is a flatworm-like organism thatlivesin close symbiosis with a photosynthetically active species of algae ( Tetraselmis convolutae ).
description
The individuals of Symsagittifera roscoffensis are egg-shaped and up to 15 mm long. The ingestion of numerous unicellular green algae gives them their characteristic green color.
distribution and habitat
The species occurs on the channel coasts of southern England and northern France as well as on the Atlantic coast of Brittany. (The specific epithet " roscoffensis " refers to the French town of Roscoff in Brittany.)
It lives in shallow, sandy, sheltered bays. It can be so common, especially in tidal pools, that it turns the water green.
nutrition
Juvenile individuals ingest the symbiotic algae without digesting them. The transition to the adult stage is associated with drastic anatomical changes: the mouth opening and esophagus are receded, while the algae spread through the tissues of the entire worm body. Up to 25,000 individual algae could be detected in a single Symsagittifera roscoffensis individual. Adult individuals are completely dependent on the algae diet. These supply them with carbohydrates and oxygen, in return the algae receive nitrogen compounds. Symsagittifera roscoffensis is therefore a fine example of a mutualistic symbiosis . Proponents of the endosymbiotic theory cite the case as a possible developmental step towards a real endosymbiosis.
swell
- ^ PM Holligan & GW Gooday: Symbiosis in Convoluta roscoffensis . In: Symposia of the Society of Experimental Biology 29 (1975), pp. 205-227.
- ^ AE Douglas: Establishment of the symbiosis in Convoluta roscoffensis . In: Journal of the marine Biological association 63 (1983), pp. 409-418.
Web links
- Biology of Convoluta roscoffensis (in English; with pictures)