5. THE PHYLUM PROTOZOA
189
prompted Kozloff to erect a new genus, Crebricoma, and to designate
C. carinata as the type. However, later, Chatton and Lwoff (1950)
pointed out that the ciliate studied by Kozloff was not Raabe’s
organism but a new species. They named it Crebricoma kozlofi. These
French workers, nevertheless, considered Raabe’s ciliate to be a member
of Kozloff’s genus Crebricoma and designated it as C . carinata.
C. kozloffi is found attached to the ctenidia and palps of Mytilus
edulis. Its relationship to its host is not clearly understood. MacKinnon
and Hawes (1961), in following Kozloff, have suggested that it may be
a true parasite “ and probably feeds on the tissues of its host ”.
Body pear-shaped, dorsoventrally flattened, 58-7 1 p
(average 64 p) long, 27-39 p (average 31 p ) wide, and 22-31 p (average
25 p ) thick, with anterior end pointed and posterior end swollen ; with
a shallow concavity on anterior portion of ventral surface containing
thigmotactic cilia ; dorsal surface and part of ventral surface behind
thigmotactic area both convex ; suctorial tentacle, by which the ciliate
is attached to host, a t anterior body terminal ; nearly all cilia contained
in thigmotactic depression on ventral body surface, arranged in thirtytwo to thirty-six rows; cilia on right, about 10-11 p long, slightly
longer than those on left of body ; large contractile vacuole present ;
macronucleus ovoid ; micronucleus spherical.
Life cycle. Nothing is known about the life cycle of C. kozlofi. It
may be speculated, however, that since this ciliate is not continuously
attached to its host but is capable of swimming, it could be actively
passed from host to host.
Kozloff (1946a) and MacKinnon and Hawes (1961)
have stated that C. k o z b f i probably feeds on its host’s tissues. Actual
histopathological changes resulting from its feeding habit have not
been studied although it has been stated that “ the damage may be
inconsiderable ”.
Description.
Pathology.
10. Crebricoma carinata, (Raabe, 1934). (Figs. 96 and 97)
(Subclass Holotrichia; order Thigmotrichida; family Ancistrocomidae)
It has been explained above in connection with C . kozlofi that
Chatton and Lwoff (1950) considered Kozloff’s C. carinata to be
distinct from Raabe’s Hypocomina carinata and have designated the
former as C . kozlofli. On the other hand, Chatton and Lwoff, in following
Jarocki (1935), believed that Raabe’s ciliate does not belong to the
genus Hypocomina but to Kozloff’s genus Crebricoma and designated
it as C . carinata. This is a relatively uncommon ciliate found on the
ctenidial surfaces of Mytilus edulis in Europe.
189
prompted Kozloff to erect a new genus, Crebricoma, and to designate
C. carinata as the type. However, later, Chatton and Lwoff (1950)
pointed out that the ciliate studied by Kozloff was not Raabe’s
organism but a new species. They named it Crebricoma kozlofi. These
French workers, nevertheless, considered Raabe’s ciliate to be a member
of Kozloff’s genus Crebricoma and designated it as C . carinata.
C. kozloffi is found attached to the ctenidia and palps of Mytilus
edulis. Its relationship to its host is not clearly understood. MacKinnon
and Hawes (1961), in following Kozloff, have suggested that it may be
a true parasite “ and probably feeds on the tissues of its host ”.
Body pear-shaped, dorsoventrally flattened, 58-7 1 p
(average 64 p) long, 27-39 p (average 31 p ) wide, and 22-31 p (average
25 p ) thick, with anterior end pointed and posterior end swollen ; with
a shallow concavity on anterior portion of ventral surface containing
thigmotactic cilia ; dorsal surface and part of ventral surface behind
thigmotactic area both convex ; suctorial tentacle, by which the ciliate
is attached to host, a t anterior body terminal ; nearly all cilia contained
in thigmotactic depression on ventral body surface, arranged in thirtytwo to thirty-six rows; cilia on right, about 10-11 p long, slightly
longer than those on left of body ; large contractile vacuole present ;
macronucleus ovoid ; micronucleus spherical.
Life cycle. Nothing is known about the life cycle of C. kozlofi. It
may be speculated, however, that since this ciliate is not continuously
attached to its host but is capable of swimming, it could be actively
passed from host to host.
Kozloff (1946a) and MacKinnon and Hawes (1961)
have stated that C. k o z b f i probably feeds on its host’s tissues. Actual
histopathological changes resulting from its feeding habit have not
been studied although it has been stated that “ the damage may be
inconsiderable ”.
Description.
Pathology.
10. Crebricoma carinata, (Raabe, 1934). (Figs. 96 and 97)
(Subclass Holotrichia; order Thigmotrichida; family Ancistrocomidae)
It has been explained above in connection with C . kozlofi that
Chatton and Lwoff (1950) considered Kozloff’s C. carinata to be
distinct from Raabe’s Hypocomina carinata and have designated the
former as C . kozlofli. On the other hand, Chatton and Lwoff, in following
Jarocki (1935), believed that Raabe’s ciliate does not belong to the
genus Hypocomina but to Kozloff’s genus Crebricoma and designated
it as C . carinata. This is a relatively uncommon ciliate found on the
ctenidial surfaces of Mytilus edulis in Europe.