School of Engineering and Science - Jacobs University

INTRODUCTION
ratios ranging between 5.2:1 and 0.15:1. Maximum growth is detected when
dinoflagellates feed on prey approximately as big as themselves (Hansen, 1992,
Naustvoll, 2000a, Naustvoll, 2000b).
Ciliates
Within the phylum Ciliata about 7500 living species are currently known from
terrestrial soils, benthic and pelagic aquatic habitats. Planktonic ciliates consume a wide
spectrum of particle sizes from bacteria to large diatoms and dinoflagellates, as well as
other ciliates. They play a crucial role as herbivorous primary consumers in marine food
webs (Urrutxurtu, 2003). A few ciliates can reach up to 2 mm in length, but most of
them span the same size range as the dinoflagellates, i.e. 20-200 µm. Mixotrophy has
been recognized as a common strategy in several ciliate genera and ciliates which retain
kleptochloroplasts can constitute a large proportion of the ciliate assemblages in coastal
waters (Stoecker et al., 1987). Several parasitic species are also known. Myrionecta
rubra is the most important photosynthetic ciliate in North Sea waters and different
Strombidium spp., e.g., Laboea strobila and Strombidium capitatum, are common
mixotrophic ciliates in the North Sea. Examples with a purely heterotrophic nutrition
are several species of the genera Strombidium, Strobilidium and Favella as well as other
tintinnids.
General characteristics
With few exceptions, the typical features of a ciliate are the rows of ciliated organelles
on the cell surface, known as kinities (during at least one stage of life). The arrangement
of these kinities on the body surface, the ciliature, is distinct in most ciliates and
conspicuous around the cell mouth or cytostome. The ciliature is used for classification
(Agatha, 2004). Ciliates are capable of very fast movements and use their cilia to propel
themselves forward through the water. At first glance two groups of ciliates can be
distinguished (Figure 6): Tintinnids - ciliates with lorica (a shell, manly consisting of a
cup shaped organic wall with or without agglutinated particles, e.g. Favella spp.,
Tintinnopsis spp.) and ciliates without lorica (e.g. Strobilidium spp., Strombidium spp.).
Characteristic for ciliates is their nuclear dualism in which the larger macronucleus is
active, while the smaller micronucleus is the germ nucleus whose meiotic products are
exchanged during sexual reproduction (Margulis et al., 1990, Lee et al., 2000). In
contrast to the dinoflagellates, asexual reproduction takes place by ‘budding’ rather than
simple cell division. Most ciliates display higher maximum specific growth rates
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