School of Engineering and Science - Jacobs University

INTRODUCTION
Two major groups are found within the dinoflagellates: Naked or athecate cell forms
(e.g. Gyrodinium spp., Gymnodinium spp., Noctiluca scintillans) and armoured or
thecate cells with thecal plates made of cellulose (e.g. Protoperidinium spp., Ceratium
spp., Dinophysis spp.) (Figure 2). The arrangement of the plates is used for species
identification in thecate forms (Dodge, 1982, Tomas, 1996, Kraberg et al., 2010). Also
characteristic of dinoflagellates is their large nucleus known as the dinokaryon. This
contains chromosomes in a highly condensed form which do not decondense during the
interphase of cell division. Vegetative cells of dinoflagellates grow by asexual cell
division (Taylor, 1987). They display maximum specific growth rates up to ~2 d -1 ,
depending on the species, but in general a division rate about 0.5-1 d -1 is common.
Feeding strategies
Heterotrophic dinoflagellates are known to catch and consume prey by a variety of
different feeding mechanisms (Schnepf & Elbrächter, 1992, Hansen & Calado, 1999).
Many naked genera (Figure 3) are able to ingest whole intact prey cells via direct
engulfment (e.g. Gyrodinium spp., Gymnodinium spp.) (Hansen, 1992). This strategy is
widespread and has recently also been described for some thecate species (Jeong et al.,
1999) (e.g. Fragilidium cf. mexicanum, Peridiniella danica). A common feeding
strategy within thecate forms is pallium feeding (Figure 4): The prey is surrounded by a
pseudopodium, the pallium, reaching out of the flagellar pore of the dinoflagellate’s
cell, and is digested outside the theca (Protoperidinium spp., the Diplopsalis group)
(Jacobson & Anderson, 1986, Hansen & Calado, 1999).
Figure 3: Direct engulfment: Gyrodinium
dominans with an ingested Scrippsiella
trochoidea cell (arrow). Scale bar 50 µm.
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