A French team has just demonstrated that the Idotée ensures the fertilization of gracilaire, red algae which appeared from hundreds of millions of years before flower plants.
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So far, the idotée populated our ribs in relative indifference. This little red crustacean, of the Isopod family, displaying less than 2 centimeters in length, hardly interests only a few marine biologists across the planet. This time is over. the publication, Thursday, July 26, of a Article of a French team, in the journal Science , promises to have it changed category and of the evocative nickname “Abeille des Mers”. Researchers at the Roscoff organic station, associated with Chilean and German laboratories, have just shown that the crustacean ensures the pollination of gracilaire by transporting the male gametes of this red seaweed to female gametes. If this mode of reproduction is usual in flower plants, it was so far unknown among algae.
Coordinator of the study, Myriam Valero had the intuition for a long time. It has been almost thirty years since the marine biologist has been studying, from every angle – from mapping to genetic analysis -, these very widespread red spaghetti, hung on rocks by a fixing disc. With a “recurring” question: “How did male and female gametes come into contact?” Because, behind their identical appearance, the gracilaire are differentiated between male and female individuals. If the first release their gametes to reproduce, the seconds keep their their own. Additional obstacle, the spermies of the red algae do not have eyelashes to move. “The dogma of marine biology wanted fertilization to be done by the only water movement, explains Myriam Valero. I had doubts. We knew that the gracilaire were covered with idotes and that the latter passed from a Algae to the other. There was no reason that they do not play a role. “
As part of her thesis, his student Emma Lavaut therefore undertook to demonstrate it. First, by comparing, in the laboratory, the reproductive success of mixed populations of gracilaire with or without crustaceans. The result has proven spectacular with up to twenty times more fertilization in the presence of idotes. “But perhaps they only move the water?” Objects the young researcher, according to scientific reasoning. The experience was therefore renewed, in two stages: the idotes were placed among male algae, then plunged into the middle of females. Reproductive success has not been denied. “And if it was the experimenter who, by his manipulation, transported the spermies?”, Continues the Thésarde. The same gestures were accomplished, but without crustaceans. And fertilization has proven to be “negligible”.
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