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(Imai & 
Rung, 1990a; Van Hoven et al., 1978), and in water 
buffalo (Dehority, 1979), to over 500,000 ml −1 in 
 musk oxen (Dehority, 1985) and in some deer 
species (Dehority, 1990, 1995; Ito et al., 1993). 
 Abundances of ciliates in non-ruminants have a sim-
ilar range: cycloposthiids numbered up to 700 ml −1
in the cecum of the capybara , representing about 
30% of the ciliate fauna (Ito & Imai, 2000a, 2000b); 
over 10,000 ml −1 throughout the intestinal tract of 
 African elephant (Eloff & Van Hoven, 1979); typi-
cally over 100,000 ml −1 in the colon of rhino ceroses
(Gilchrist et al., 1994) and caecum of horses 
(Bonhomme-Florentin, 1994); and abundances 
of ophryoscolecids of around 1,000,000 ml −1 in 
 collared peccary (Carl & Brown, 1983). 
 The rumen ciliates have diverse interactions with 
the bacterial and fungal communities and with each 
other. Bacteria are the foundation of the rumen eco-
system, colonizing substrates minutes after inges-
tion and forming cellulolytic consortia that digest 
the plant tissues (McAllister, Bae, Jones, & Cheng, 
1994). While most rumen ciliates ingest bacteria 
as a source of nitrogen , Entodinium species are 
particularly important predators of bacteria, con-
suming more than 10 5 bacteria per ciliate per hour 
(Coleman, 1989; Williams, Joblin, Butler, Fonty, 
& Bernalier, 1993). Entodiniomorphids are able to 
ingest plant fragments and digest these using their 
own cellulolytic enzymes (Akin & Amos, 1979; 
Bauchop, 1979; Benyahya, Senaud, & Bohatier, 
1992; Bohatier, Senaud, & Benyahya, 1990; Grain 
& Senaud, 1985; Michalowski, Belzecki, Kwiatkowska, 
& Pajak, 2003; Stan, Belzecki, Kasperowicz, 
9.2 Life History and Ecology 193
Kwiatkowska, & Michalowski, 2006), and even chitin
(Belzecki & Michalowski, 2006). Polysaccharides 
are stored as amylopectin , either as skeletal plates 
or as cytoplasmic particles. Eadie (1967) was 
one of the first to recognize that there were some 
ciliates that were consistently common in the 
 rumen , namely Entodinium spp., Isotricha spp. 
and Dasytricha ruminantium while others varied. 
Eadie (1967) identified two assemblages, Type A 
and Type B. The Type A assemblage included 
Polyplastron multivesiculatum , Diploplastron aff-
ine , and Ophryoscolex tricoronatus , while the 
Type B assemblage included Eudiplodinium mag-
gii , Epidinium spp., Eremoplastron spp., and 
Ostracodinium spp. The Type A assemblage typi-
cally displaces Type B as the former includes some 
predators of the latter (Eadie; Imai, Katsuno, & 
Ogimoto, 1979). Eudiplodinium maggii may be 
induced to develop to a larger size in the pres-
ence of its predator Polyplastron multivesiculatum
(Eadie, 1979). Polyplastron multivesiculatum , 
E. maggii , and Entodinium sp. may also ingest fungal 
zoospores and rhizoids (Williams et al., 1993). 
Finally, Isotricha and Dasytricha species preferen-
tially ingest starch grains . This feeding habit may 
provide a more stable rumen pH since it prevents 
the more rapid bacterial fermentation of starch to 
 lactic acid , which may lead to lactic acid acidosis 
(Williams, 1986). Since most of the ciliates are 
retained in the rumen (Bonhomme-Florentin, 1994; 
Williams, 1986), ciliate biomass contributes little to 
host metabolism. Moreover, although both ciliates 
and bacteria are highly cellulolytic , bacterial activ-
ity can entirely replace the ciliate activity (Hidayat, 
Hillman, Newbold, & Stewart, 1993). Although 
there are contradictory reports, typically defauna-
tion or removal of the ciliates has little or no impact 
on host growth (see reviews of Bonhomme, 1990; 
Jouany, 1994; Veira, 1986; Williams, 1986). Some 
recent research has demonstrated that defaunation 
improves ruminal nitrogen metabolism to the host 
(Ivan, Neill, & Entz, 2000; Koenig, Newbold, 
McIntosh, & Rode, 2000). 
 Bonhomme-Florentin (1994) noted that there 
is very little research on the importance of the 
ciliates of non-ruminant and primate hosts. Like 
their rumen relatives, Cycloposthium and Didesmis
associate with plant fibres in the caecum of the 
horse, aiding in the digestion of these fibres 
(Bonhomme-Florentin, 1985). However, Moore 
and Dehority (1993) concluded that ciliates do not 
play an essential role in the equine hindgut : defau-
nation of the caecum and colon had no effect on 
levels of cellulose digestion . 
 One major impact of defaunation is reduction 
of methane production by the ruminant . Like the 
sapropelic armophoreans (see Chapter 8 ), metha-
nogenic bacteria are associated as epibionts on 
entodiniomorphids (Krumholz, Forsberg, & Veira, 
1983; Stumm, Gijzen, & Vogels, 1982) and as 
endosymbionts in vestibuliferidans (Finlay et al., 
1994). These methanogens have been assigned to 
the genera Methanobrevibacter , Methanosphaera , 
and Methanosarcina (Hillman, Lloyd, & Williams, 
1988; Tokura, Chagan, Ushida, & Kojima, 1999). 
Adult cattle can produce from 300–600 l of methane 
per day, translating to 80 million tonnes of methane 
worldwide (Jouany, 1994). This methane produc-
tion may represent the greatest source of methane 
production in the European Union (Moss, Jouany, 
& Newbold, 2000) and over 50% of the methane 
emissions in Australia (Klieve & Hegarty, 1999). 
 Defaunation to reduce methane production is thus 
a major priority in the context of global warming . 
Adding coconut oil to artificial rumen fermenters
reduced methane formation by 40% (Dohme et al., 
1999) while the common food preservative, nisin , 
reduced methanogen production by 36% (Klieve & 
Hegarty, 1999). There are other strategies for elimi-
nating the protozoa, but as yet none have reached 
commercialization (Hegarty, 1999). 
 With the exception of Balantidium , trichostome 
ciliates do not form cysts . Thus, transmission from 
one host to the other must take place by various 
forms of contamination . Rumen ciliates and those 
in the forestomach of the host are transferred by 
 salivary contamination from mother to offspring 
and contamination of drinking water (Bonhomme-
Florentin, 1994; Van Hoven, 1978). Entodinium is 
typically the first rumen ciliate to appear (Crha, 
Stříž, Skřivánek, & Valach, 1991). Young horses 
become infected by actively eating the mothers’ 
 feces in the first week of life (Ike, Imai, & Ishii, 
1985). It is not yet known how the macropodiniids 
are transmitted between marsupial hosts, although 
 maternal grooming of the young may be a typical 
route (Cameron & O’Donoghue, 2003b). 
 The feeding preferences and strategies of lito-
stomes are quite diverse. As noted above for the 
 trichostomes , bacteria and plant material can be 
prey items in addition to other ciliates. The hap-
torians can be typified as fast-swimming, active 
and voracious predators, showing marked prefer-
ences for flagellates and other ciliates, even to 
becoming cannibalistic . Dragesco (1962) used high 
speed cinematography to provide some detailed 
descriptions of predation by Enchelys , Litonotus , 
Chaenea , Didinium , and Dileptus on other ciliates, 
like Colpidium . Feeding by Dileptus may even be 
entrained to a daily rhythm (Miller, 1968). This 
preference of haptorians for flagellates and other 
 ciliates has been confirmed by others (e.g., Dolan 
& Coats, 1991b; Estève, 1982; Foissner & Leipe, 
1995; Foissner, Berger, & Schaumburg, 1999; 
Johnson, Donaghay, Small, & Sieburth, 1995). In 
an ingenious series of experiments, Karpenko, 
Railkin, and Seravin (1977) used magnetic moving 
models to demonstrate that Didinium and Dileptus
responded to prey movement, somehow sensing 
 hydrodynamic disturbances of the medium. This 
sensitivity to hydromechanical signals has been 
confirmed for Mesodinium pulex , which probably 
uses its bristle girdle as the “detector”