Ref ID : 7668
Karl G. Grell and Anne Meister; [Die Ultrastruktur von Acinetopsis rara Robin (Suctoria) I. Tentakeln und Nahrungsaufnahme]. Protistologica XVIII(1):67-84, 1982
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1. The marine suctorian Acinetopsis rara has a long capturing tentacle by which it draws its prey, the cell body of the suctorian Ephelota, from its stalk. Electron microscopical observations prove that the capturing tentacle, which can be extended up to a length of one mm, serves also for the ingestion of food. Its ultrastructure is that of an ordinary suctorian tentacle. 2. The numerous short feeding tentacles, however, are specialized for food intake only. They have a reduced knob, equipped with none or only a few haptocysts. 3. After the fusion of the predator's and prey's cell membranes, the knob of the feeding tentacle penetrates the cell body of the Ephelota. During this process the distal ends of the overlapping microtubular ribbons of the axoneme enter the knob and splay outwards in a fountain-like manner, a positional change connected with torsion. 4. Underneath the splayed microtubular ribbons, radial outgrowths of the tentacular knob are formed, to be called "villi". Their number corresponds with that of the ribbons. The membrane of the "villi" is covered with a "layer of contact" which establishes a firm connection with the epiplasmic layer of the Ephelota. 5. In this way the feeding tentacles of Acinetopsis form stationary "organelles of anchorage" which prevent the prey's drifting away in the turbulent environment of marine litoral. 6. Though Acinetopsis exhibits a true dimorphism of tentacles, it is quite different from that of Ephelota, where the capturing tentacles serve only to capture prey and the feeding tentacles only to take in food. Ultrastructure is a mirror - image of this difference.