Page 144 - Algae Anatomy, Biochemistry, and Biotechnology

Anatomy 127

FIGURE 2.84 Undischarged trichocyst of Goniaulax poliedra in longitudinal and transverse sections.

Feeding structures are present in dinoflagellates, depending on the type of feeding mechanisms
present: feeding tube (peduncle, or tentacle) and feeding veil (pallium). Tube feeding is commonly
found among both naked and thecate species of dinoflagellates (e.g., Dinophysis, Amphidinium,
Gyrodinum, and Peridinopsis). Cell membrane is extruded from the cell to form a tube, which
can engulf whole cells or penetrate prey cell walls and suck in prey cytoplasma.
Pallium feeding has been described only for heterotrophic thecate species such as Protoperidi-
nium and Diplopsalis. The prey is captured via a primary attachment filament; an extension of the
cytoplasm then emerges from the region of the sulcus-cingulum, which encloses the prey as a veil
(pallium). Enzymatical digestion of the prey cytoplasm is brought about inside the veil and the
products are then transported to the predator.
Direct engulfment is mainly found among naked species (e.g., Gyrodinium, Gymnodinium, and
Noctiluca); recently, however, some thecate species have been shown to use this feeding mechan-
ism as well. Feeding behavior in dinoflagellates involves several steps prior to actual ingestion,
including precapture, capture, and prey manipulation. As feeding mechanisms allow the ingestion
of relatively large preys, or parts thereof, dinoflagellates are regarded as raptorial feeders. While
prey size plays an important role for the ability of dinoflagellates to ingest food, this cannot
alone explain prey preferences actually found. Some dinoflagellate species can be very selective
in their choice of prey, while others show a remarkable versatility.