Symsagittifera roscoffensis
Symsagittifera roscoffensis
Symsagittifera roscoffensis is a flat worm-like organism in close symbiosis with photosynthetic algae ( Tetraselmis convolutae ) lives.
Description
The individuals of Symsagittifera roscoffensis are ovate, up to 15 mm long. The inclusion of numerous unicellular green algae they get 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 Brittany Atlantic coast. ( The epithet " roscoffensis " refers to the French town of Roscoff in Brittany. )
She lives in shallow, sandy and sheltered bays. Especially in tide pools they may be so common that it colors the water green.
Nutrition
Juvenile individuals take on the symbiotic algae without digesting them. The transition to the adult stage is associated with drastic anatomical changes: mouth and esophagus are regressed, while the algae spread in the tissues of the entire worm body. In a single - Symsagittifera roscoffensis individual up to 25,000 individual algae could be detected. Adult individuals are completely dependent on diet by the algae. These provide them with carbohydrates and oxygen, in return, the algae get nitrogen compounds. Symsagittifera roscoffensis is thus an excellent example of a mutualistic symbiosis. The case is cited as a possible evolutionary step towards a true endosymbiosis Proponents of the endosymbiont theory.