Phagotrophy in Gymnodinium Fungiforme (Pyrrhophyta): The Peduncle as an Organelle of Ingestion¹

The non‐photosynthetic phagotrophic dinoflagellate, Gymnodinium fungiforme Anissimova, ingests prey cytoplasm through a highly extensible structure called the peduncle. Although the peduncle is not observable when G. fungiforme is swimming, it protrudes 8–12 μm from the sulcal‐angular vicinity of the cell during feeding, and is approximately 3.3 μm wide when the cytoplasm of its prey is flowing through it. A circular‐oval ring of overlapping microtubules, the ‘microtubular basket’ may be seen in transmission electron microscope sections of G. fungiforme and it is inferred that this structure is a cross section of a retracted peduncle. The microtubular basket‐peduncle complex is discussed in relation to similar structures in other dinoflagellates and to the tentacle of the suctorian ciliates which have a homologous ingestion system.