Cap 7

food for these 
ciliates (Laval-Peuto & Febvre, 1986; Stoecker, 
Silver, Michaels, & Davis, 1988/1989). These 
 chloroplasts remain functional for several days in 
Laboea and Strombidium , enabling the ciliate to 
fix carbon during this time (Perriss, Laybourn-
Parry, & Jones, 1994; Stoecker, Michaels, & Davis, 
1987a; Stoecker, Silver, Michaels, & Davis, 1988). 
 Mixotrophy may serve a variety functions for the 
ciliate, including providing fixed carbon during 
periods when prey are not abundant (Dolan & 
Pérez, 2000; Stoecker et al., 1987a) and oxygen in 
those species that prefer to live at the oxic-anoxic 
boundary in freshwater ponds (Berninger, Finlay, 
& Canter, 1986). 
 As abundant components of aquatic ecosystems, 
 spirotrichs can also be consumed by other organ-
isms, serving as links to higher trophic levels 
(Sanders & Wickham, 1993). Choreotrichs and 
 tintinnids are consumed by rotifers (Gilbert & 
Jack, 1993), copepods (Burns & Gilbert, 1993; 
Gismervik, 2006; Pérez, Dolan, & Fukai, 1997; 
Stoecker & Sanders, 1985; Turner, Levinsen, 
Nielsen, & Hansen, 2001; Wiackowski, Brett, 
& Goldman, 1994; Wickham, 1995), cladocer-
ans (Jack & Gilbert, 1993; Wickham & Gilbert, 
1991; Wickham, Gilbert, & Berninger, 1993), 
 barnacle nauplii (Turner et al., 2001), euphausiids 
(Nakagawa, Ota, Endo, Taki, & Sugisaki, 2004), 
 scyphozoan jellyfish (Stoecker, Michaels, & Davis, 
1987b), larval and post-larval ctenophores (Stoecker, 
Verity, Michaels, & Davis, 1987c), nematode worms 
7.2 Life History and Ecology 153
154 7. Subphylum 2. INTRAMACRONUCLEATA: Class 1. SPIROTRICHEA
(Hamels, Moens, Muylaert, & Vyverman, 2001), 
freshwater oligochaetes (Archbold & Berger, 
1985), oysters (Loret et al., 2000), and larval 
 fish (Nagano, Iwatsuki, Kamiyama, & Nakata, 
2000; Olivotto et al., 2005; Stoecker & Govoni, 
1984). They are even consumed by other protists, 
both ciliates and dinoflagellates (Bockstahler & 
Coats, 1993; Dolan, 1991; Smalley & Coats, 2002; 
Smalley, Coats, & Adam, 1999). 
 Planktonic ciliates, in their turn, have inde-
pendently evolved jumping movements to escape 
predation (Tamar, 1979). In the case of the suspen-
sion feeding crustaceans, the choreotrichs , like 
Strobilidium , and the stichotrich Halteria have 
independently evolved a jumping behavior that 
significantly reduces encounters with predators 
(Gilbert, 1994), even relative to loricate tintinnids
(Broglio, Johansson, & Jonsson, 2001). The ciliates
are apparently responding to a hydromechanical 
signal, very likely deformations of fluid flows 
caused by the suction-feeding currents of the pred-
ators (Jakobsen, 2000, 2001). Euplotes undergoes 
an “ escape response ” in the presence of the turbel-
larian predator Stenostomum (Kuhlmann, 1994). 
 For “softer”-bodied predators, like other ciliates, 
 oligochaetes , and turbellarians , Euplotes species 
develop an enlarged circular, ‘winged’ form that 
is much less easily consumed (Fyda, Warren, & 
Wolinska, 2005; Kuhlmann & Heckmann, 1985, 
1994; Kusch, 1995). This ‘winged’ form develops 
under the influence of a diffusible protein morphogen
or kairomone when the ciliate predator is Lembadion
(Kuhlmann & Heckmann; Peters-Regehr, Kusch, 
& Heckmann, 1997). The kairomone induces the 
assembly of new microtubular structures to support 
the ‘wings’ (Jerka-Dziadosz, Dosche, Kuhlmann, 
& Heckmann, 1987). Onychodromus quadricornutus
develops large dorsal spines in response to the 
predator Lembadion (Wicklow, 1988), although the 
ultrastructural basis of this development has not yet 
been determined. These morphological defenses are 
genetically variable among clones, suggesting that 
 natural selection can act on them to favor the more 
fit variants (Duquette, Altwegg, & Anholt, 2005;
Wiackowski, Fyda, Pajdak-Stós, & Adamus, 2003).
 Marine Euplotes species also secrete a variety of 
 terpenoids , which are strain and species specific. 
These have been shown to have biological activity, 
killing both conspecifics that could be potential 
competitors (Dini, Guella, Giubbilini, Mancini, & 
Pietra, 1993) and predators, such as the haptorian 
Litonotus (Guella, Dini, & Pietra, 1995; Guella, 
Dini, & Pietra, 1996). The most bizarre predator 
defense , probably among all the ciliates, is that 
exhibited by the hypotrich Euplotidium : it carries 
 bacterial ectosymbionts that explode on contact 
with the predatory ciliate Litonotus , defending 
their host against predation (Verni & Rosati, 1990; 
Petroni, Spring, Schleifer, Verni, & Rosati, 2000)! 
 Symbionts of spirotrichs can be categorized 
as both beneficial (i.e., mutualistic ) and harmful 
(i.e., parasitic ). Bacteria , as in Euplotidium above, 
have been observed on the outside of tintinnid 
loricae, and also as intracellular forms (Laval-Peuto,
1994). Their role in tintinnids is not known. However, 
both freshwater and marine species of the hypot-
rich Euplotes depend upon bacterial symbionts 
for cell growth. Aposymbiotic Euplotes fail to 
divide and ultimately die (Heckmann, 1975, 1983; 
Heckmann & Schmidt, 1987; Heckmann, Ten 
Hagen, & Görtz, 1983; Vannini, Schena, Verni, & 
Rosati, 2004). However, Fujishima and Heckmann 
(1984) rescued aposymbiotic freshwater Euplotes
by transfer of bacterial symbionts even among 
species of Euplotes , suggesting that the common 
ancestor of this group of Euplotes species inher-
ited a hereditary defect in cell division that was 
rescued by its bacterial endosymbiont . At the other 
extreme, some bacterial endosymbionts carried by 
Euplotes species kill sensitive cells of the same 
species, either by liberating toxins into the medium 
or by transfer of toxins and bacteria during mat-
ing, a phenomenon also reported in Paramecium
species (Verni, Rosati, & Nobili, 1977; see review 
by Heckmann, 1983). Fenchel and Bernard (1993) 
have described an unusual association between the 
obligately anaerobic Strombidium purpureum and 
its photosynthetic purple non-sulphur bacteria , an 
analogy to the symbiosis that is believed to have 
lead to the evolution of mitochondria. 
 Eukaryotic symbionts of spirotrichs have also 
been observed. Chlorella species are often found 
in hypotrichs and stichotrichs , whose photobe-
havior may be influenced by the presence of 
the symbiont (Reisser, 1984; Reisser & Häder, 
1984). These Chlorella species are typical photo-
synthetic symbionts that presumably at least 
provide organic sugars to their hosts. Other 
protists are not as friendly. Species of the kineto-
plastid Leptomonas infect the macronucleus of the 
 stichotrich Paraholosticha sterkii and the hypot-
rich Euplotes , causing death in some strains of 
these species (Görtz & Dieckmann, 1987; Wille, 
Weidner, & Steffens, 1981). One of the most unu-
sual flagellate infections of spirotrichs is that of 
the parasitic dinoflagellate Duboscquella (Coats, 
1988; Coats, Bockstahler, Berg, & Sniezek, 1994). 
Species of Duboscquella that kill the tintinnid 
host may even regulate host abundances in natural 
populations (Coats & Heisler, 1989). Foissner and 
Foissner (1986) have described a zoosporic fun-
gus , Ciliomyces spectabilis , that invades and kills 
the cysts of the stichotrich Kahliella simplex . 
 Spirotrichs have complex behaviors that have 
been extensively investigated. Ricci and his research 
group have introduced the ethogram as a quantita-
tive approach to characterizing behavior, especially 
of hypotrichs and stichotrichs (e.g., Banchetti, Erra, 
Ricci, & Dini, 2003; Leonildi, Erra, Banchetti, & 
Ricci, 1998; Ricci, 1990; Ricci, Cionini, Banchetti, 
& Erra, 1999). In addition to thigmotactic responses 
by benthic forms to the texture of substrate surfaces 
(Ricci, 1989) and water current (Ricci et al., 1999), 
 planktonic forms demonstrate a negative geotaxis 
that is influenced by temperature and light and 
that explains their vertical