180
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
attached by their thigmotactic cilia but will leave the substratum
constantly and flutter up to the surface in a series of jerky somersaults
and then return to the bottom. These investigators have expressed the
opinion that : " These free-swimming intervals may account for crossinfections (between hosts) ".
Certain cilia of A . mytili, like those of the other thigmotrichs, are thigmotactic and are employed for attachment. Kidder
(1933~) has reported that while swimming, this ciliate engages in
" jerky flights ", a phenomenon which has also been noted by MacKinnon and Hawes (1961).
Physiology. Nothing is known about the physiology of A. mytili
trophozoites. Raabe (1936) has found that encysted forms will excyst
in 7-8 h when cysts are maintained a t room temperature.
Pathology. As far as is known, A. mytili causes no serious damage
to its host, although Pauley et al. (1966), in an abstract, reported that:
It appears that ciliates ( A . mytili and A . caudatum) are potential pathogens,
capable of infecting a large number of individuals (Mytilis edulis) within
a shellfish population and causing pathological changes in the hosts, under
certain adverse conditions when the bivalves are weakened.
Proof of this remains to be contributed.
Ecology.
2 . Ancistrum cylidioides Issel, 1903. (Figs. 80-82)
(Subclass Holotrichia; order Thigmotrichida; family Hernispeiridae)
Issel (1903), in his paper dealing with thigmotrichs collected in the
Gulf of Naples, described five new species of Ancistrum. Among these,
A . cylidioides was described from the gill surfaces of the amphineuran
Chiton olivaceus, the gastropod Natica habraea, and the pelecypods
Tellina exigua, Capsa fragilis, Donax trunculus and Tapes decussatus.
Since T . decussatus is of some commercial importance, this ciliate is
being included herein.
I n addition to A. cylidioides, Issel described A. compressum from
C q s a fragilis, A. tellinae from Tellina exigua, A. subtruncatum from
Tapes decussatus, and A . barbatum from the gastropods Murez trunculus
and Fusis syracusanus.
Body ovoid when viewed laterally, slightly pointed
posteriorly, right side of body strongly convex, left side almost
straight, dorsal and ventral surfaces slightly convex, 27-33 p long
x 13-18 , u wide ; seven ciliary rows on right surface, eleven to twelve
on left surface ; with long sweeping cilia on right side of body, cytostome as marginal invagination a t anterior limit of posterior oneDescription.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
attached by their thigmotactic cilia but will leave the substratum
constantly and flutter up to the surface in a series of jerky somersaults
and then return to the bottom. These investigators have expressed the
opinion that : " These free-swimming intervals may account for crossinfections (between hosts) ".
Certain cilia of A . mytili, like those of the other thigmotrichs, are thigmotactic and are employed for attachment. Kidder
(1933~) has reported that while swimming, this ciliate engages in
" jerky flights ", a phenomenon which has also been noted by MacKinnon and Hawes (1961).
Physiology. Nothing is known about the physiology of A. mytili
trophozoites. Raabe (1936) has found that encysted forms will excyst
in 7-8 h when cysts are maintained a t room temperature.
Pathology. As far as is known, A. mytili causes no serious damage
to its host, although Pauley et al. (1966), in an abstract, reported that:
It appears that ciliates ( A . mytili and A . caudatum) are potential pathogens,
capable of infecting a large number of individuals (Mytilis edulis) within
a shellfish population and causing pathological changes in the hosts, under
certain adverse conditions when the bivalves are weakened.
Proof of this remains to be contributed.
Ecology.
2 . Ancistrum cylidioides Issel, 1903. (Figs. 80-82)
(Subclass Holotrichia; order Thigmotrichida; family Hernispeiridae)
Issel (1903), in his paper dealing with thigmotrichs collected in the
Gulf of Naples, described five new species of Ancistrum. Among these,
A . cylidioides was described from the gill surfaces of the amphineuran
Chiton olivaceus, the gastropod Natica habraea, and the pelecypods
Tellina exigua, Capsa fragilis, Donax trunculus and Tapes decussatus.
Since T . decussatus is of some commercial importance, this ciliate is
being included herein.
I n addition to A. cylidioides, Issel described A. compressum from
C q s a fragilis, A. tellinae from Tellina exigua, A. subtruncatum from
Tapes decussatus, and A . barbatum from the gastropods Murez trunculus
and Fusis syracusanus.
Body ovoid when viewed laterally, slightly pointed
posteriorly, right side of body strongly convex, left side almost
straight, dorsal and ventral surfaces slightly convex, 27-33 p long
x 13-18 , u wide ; seven ciliary rows on right surface, eleven to twelve
on left surface ; with long sweeping cilia on right side of body, cytostome as marginal invagination a t anterior limit of posterior oneDescription.