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VOL. 72 (3), 391-408, 2006 HARMFUL ALGAL BLOOMS, RED TIDES AND HUMAN...

protists (˜ 4000 species), which exhibit a great diversity in size (from
a few µm to 2 mm), form and lifestyle (Figure 1). Ninety percent of
all dinoflagellates are marine plankton, and the rest are benthic,
freshwater or parasitic species. About half the species are free-
life photosynthetic organisms, and the others are heterotrophic
predators on bacteria, microalgae, other protists (including other
dinoflagellates), fish eggs, saprophytes, take up residence within other
organisms as symbiotic partners, and even parasites. Dinoflagellate
biology is reviewed in detail in Lee (12) and Graham and Wilcox (7).

FIGURE 1. Red tide and red tide-producing species. a) red tide producing
dinoflagellate (Noctiluca); b) PSP tide producing dinoflagellate (Gymnodinium);

c) DSP producing dinoflagellae (Prorocentrum).

Dinoflagellates also present fascinating nuclear features that have
intrigued researchers for many years (13-14). As examples, a dense
nuclear matrix accommodates permanently condensed chromosomes
that are composed by fibbers organized without histones and
nucleosomes in stacked rows of parallel nested arches (Figure 2).
The macromolecular chromosome structure corresponds to
cholesteric liquid crystals with a constant left-handed twist. RNA is
determinant to maintain the chromosome structure. Whole mounted

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