Observations by Means of Cine Photography on the Behaviour of the Haptonema in Plankton Flagellates of the Class Haptophyceae

Abstract
INTRODUCTIONInitially the haptonema was recorded as a ‘little additional flagellum’ by Scherffel (1899) when he describedPhaeocystis globosa. Similarly, the haptonema was referred to as the ‘third flagellum’ on the apparently tri-flagellate, brackish-waterPrymnesium saltansMassart (Massart, 1920). Two further brackish water species ofPrymnesiumwere described by Carter (1937) and all were characterized by a very short immobile ‘third appendage’. Lackey (1939) found a freshwater organism similar toPrymnesiumbut it possessed a ‘third flagellum’ several times the length of the true flagella. He re-corded that the third appendage was held out rigidly when the cell was at rest but during rapid swimming he was unable to see it and thought that this was due to an extremely rapid beat. He named his new organismChrysochromulina parvaandC. parvaLackey is now the type species of a considerable genus.Parke, Manton & Clarke (1955,1956,1958,1959) made a study of the light microscopy and fine structure of numerous marine species ofChrysochromulina. Their results showed that the ‘third flagellum’ differed in appearance and structure from that of a true flagellum and hence they decided to call this organelle ahaptonemaowing to its thread-like form and its ability to adhere to a smooth surface (Parke, Manton & Clarke, 1955). Their observations revealed that the haptonema could attach to a surface by an ‘adhesive tip’ and that the majority of species could coil their haptonemata into a helix and extend it again. In some species, e.g.C. strobilus(Parke, Manton & Clarke, 1959), the haptonema was usually tightly coiled whilst the cell was swimming.

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