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1988; Kazubski & Migała, 1974; Lom, 1995; 
Lom & Nigrelli, 1970; Urawa, 1992). Some unu-
sual species have even invaded other vertebrates: 
Kyaroikeus species are found in the respiratory 
tracts of several species of odontocete cetaceans 
(Sniezek et al., 1995). 
 Chonotrichs as ectosymbionts of crustaceans , 
are probably restricted in their distribution by the 
distribution of their hosts. However, our knowledge 
of these ciliates is fragmentary. Most species are 
found on the mouth parts and gills of marine crusta-
ceans and have been found on crustaceans in all the 
world’s oceans (for some examples, see Fernández-
Leborans & Gabilondo, 2006; Fernández-Leborans 
& Sorbe, 1999; Jankowski, 1973b; Mohr et al., 
1970; Morado & Small, 1995). The review by 
Fernández-Leborans (2001) provides a good 
entry into the literature. Chonotrich species appear 
to show very high site specificity to their host and 
even a particular body region on the host, although 
experimentation has yet to confirm this conclusion 
(Jankowski, 1973b). Spirochona , Cavichona , and 
Serpentichona , the only freshwater chonotrichs , 
typically infest the gills of freshwater gamma-
rid amphipods worldwide (Fernández-Leborans, 
2001; Jankowski, 1973b; Mohr et al.; Stloukal & 
Matis, 1993). Isochonids are hyperparasites, found 
on the copepod Balaenophilus , which itself is a 
parasite of baleen whales ! Batisse (1994a) noted 
that chonotrichs are very delicate ciliates, which 
do not survive long without their hosts and even 
when the host is removed from its natural habitat. 
Consequently, our knowledge of their natural his-
tory is quite limited. The swarmers or buds are 
undoubtedly the dispersal phase, distributing the 
species over the host as colonization proceeds and 
distributing the species between hosts. When hosts 
are moulting , polygemmy or repeated budding 
without intervening growth may occur, providing 
many propagules likely to increase the chances of 
recolonization of the newly moulted host (Batisse, 
1994a). Observations suggest that chonotrichs are 
omnivorous ciliates, feeding on tissue debris, cuti-
cle pieces, bacteria , diatoms , and other protists. 
However, some chonotrichs can be quite selective, 
preferring bacteria and other protists (Batisse, 
1994a). There has been no experimentation to sup-
port this observations. 
 Rhynchodians show two different life histories, 
conforming to the two major taxonomic groups 
into which they are divided. Both groups feed using 
their tentacle-like mouthparts, probably consuming 
prey cytoplasm. The hypocomatids blur the distinc-
tion between predator and parasite, for they feed 
upon suctorians and peritrichs that are often larger 
than themselves and some species are found as 
parasites in ascidians (Burreson, 1973; Chatton & 
Lwoff, 1939b) and barnacles (Jankowski, 1967c). 
 Hypocomatid -like ciliates were likely ancestors 
to the rhynchodids , which are all obligate para-
sites. Rhynchodids typically parasitize marine and 
freshwater bivalve molluscs (Bower & Meyer, 
1993; Dobrza ska, 1959, 1961, Molloy, Karatayev, 
Burlakova, Kurandina, & Laruelle, 1997; Raabe, 
1970b), but they have also been reported on chi-
tons , gastropods , and even sabellid polychaete 
 annelids (Kozloff, 1961, 1965a). Host specificity 
of rhynchodids can be quite strict and there is 
even demic variation among ciliates isolated from 
individuals of the same host species (de Puytorac, 
1994b). Adjacent hosts are likely infected by cili-
ates that swim from one host to the next (Chatton 
& Lwoff, 1950; Fenchel, 1965a). Nevertheless, 
 infections by rhynchodids rarely reach intensities 
that cause harm to their hosts. 
 Suctorians attach to the substratum by a non-
contractile stalk or directly by the body. The proteina-
ceous materials used for attachment are extremely 
resistant to mechanical and chemical degradation 
(Batisse, 1994b). The substrate may be a biofilm on 
10.2 Life History and Ecology 217
an inorganic substrate, on aquatic plants, or on the 
body surface of animals. Thus, suctorians can be 
both free-living or symbiotic, and are probably the 
most widespread symbiotic group in the phylum. 
They are found in marine and freshwater habitats, 
in soils and mosses and have been recorded on all 
continents (e.g., Collin, 1912; López-Ochoterena, 
1966; Wang, 1977). There are also some species 
that are found in the plankton . Symbiotic spe-
cies are often found on crustaceans (Fernández-
Leborans & Tato-Porto, 2000a; Morado & Small, 
1995). Acineta and Tokophrya are two common 
genera that are found as free-living species or 
as facultative ectosymbionts, along with other 
 suctorians , on copepods (Evans, Sell, & Beeton, 
1981; Fernández-Leborans & Tato-Porto, 2000b; 
Grigorovich, Dovgal, MacIsaac, & Monchenko, 
2001), isopods (Fernández-Leborans, Hanamura, & 
Nagasaki, 2002; Olafsdottir & Svavarsson, 2002), 
 mysids (Fernàndez-Leborans & Tato-Porto, 2002), 
 decapods (Fernàndez-Leborans & Gabilondo, 
2006; Fernàndez-Leborans, Córdoba, & Gómez, 
1997; Granados & Chinchilla, 1990; Vogelbein 
& Thune, 1988), and amphipods (Fernàndez-
Leborans, Arndt, & Gabilondo, 2006; Walker & 
Roberts, 1982). The migratory swarmer , which 
is undescribed in many species, is the stage that 
infects new hosts or increases the colonization 
of the current host. Swarmers may be small and 
ciliated or large, worm-like and incapable of swim-
ming. In the Laurentian Great Lakes , reinfestation 
of copepods by Tokophrya quadripartita occurs on 
a seasonal basis with peak prevalences of infesta-
tion found in the summer months (Evans, Sicko-
Goad, & Omair, 1979). Suctorians can be broadly 
distributed on the appendages of their crustacean 
hosts (e.g., Batisse, 1986; Fernàndez-Leborans & 
Tato-Porto, 2002; Nicol, 1984; Walker & Roberts) 
while others can show high site specificity (e.g., 
Batisse, 1973; Hitchen & Butler, 1972). The inten-
sity of the suctorian infestation has been correlated 
to the age of the host: mature hosts can have almost 
ten times the number of suctorians as juvenile 
hosts (Fernàndez-Leborans & Tato-Porto, 2002). 
Several unusual suctorians even colonize the out-
side of vertebrates, such as on the shell of turtles 
(Goodrich & Jahn, 1943) and the gills of Arctic 
char (Hofer, Salvenmoser, & Fried, 2005). At 
least two genera colonize the inside of vertebrates: 
Allantosoma is found in the cecum and colon of 
 horses (Imai, 1979; Sundermann & Paulin, 1981); 
and Cyathodinium in the caecum of guinea pigs 
(Paulin & Corliss, 1964). 
 Suctorians feed primarily on other ciliates , typi-
cally showing little preference. However, haptorians 
and heterotrichs generally appear to be immune 
to suctorian predation (Batisse, 1994b). There 
is nevertheless some diversity in feeding habits. 
For example, Trematosoma may feed on bacteria 
(Batisse, 1973), Choanophrya feeds on particles 
of food debris derived from its copepod host 
(Hitchen & Butler, 1973a), and Phalacrocleptes
feeds on the tissues of its polychaete host (Kozloff, 
1966). Finally, there are some suctorians that are 
relatively small compared to their ciliate “prey” or 
host so that they have been described as parasites 
(Matthes, 1971). Podophrya species attach to the 
outside of their “host” ciliate, a Nassula species 
(Fauré-Fremiet, 1945) or Paramecium or Urostyla
(Jankowski, 1963) or even become “internal” pred-
ators (Fig. 10.5). Pseudogemma species attacks 
the suctorian Acineta (Batisse, 1968). Podophrya
may reach abundances sufficient to sometimes 
control Nassula populations (Canter, Heaney, & 
Lund, 1990). Pottsiocles invades its folliculinid 
 heterotrich host (Chatton & Lwoff, 1927) while 
Endosphaera is found in the cytoplasm of trichodi-