208
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
pointed out that a t least some of the trematodes which Tennent believed
to be B. cuculus metacercariae and adults could have been those of a
species of Rhipidocotyle. It should be pointed out, however, that
Tennent (1909) did prove that eggs or miracidia from an unknown
adult bucephalid in the gar, Lepasdosteus osseus, could infect Crassostrea
virginica and develop into sporocysts which grow for a t least one month.
However, whether this parasite of the gar is B. cuculus is not known.
Ecology. According to Hopkins (1954a), B. cuculus, from what is
known, occurs in oysters from New Jersey to Texas, but its distribution
is not continuous throughout this range. It is also known that the
incidence of infection in Crassostrea virginica is highest in small
landlocked estuaries.
Physiology. Nothing is known about the physiology of 3. cuculus
except that it apparently cannot survive high salinities.
Pathology.
A detailed histopathological study of Crassostrea
virginica parasitized by B. cuculus has not yet been made although
certain pathological changes are known. It is known that B. cuculus
sporocysts utilize the oyster's gonads as the primary site of infection,
and in so doing usually cause parasitic castration. As the sporocysts
increase in length and undergo further branching, practically all of
the organs of its host, except the foot, become infiltrated. Whether
the parasite will eventually kill the oyster has not been studied under
controlled conditions. Hopkins (1957a), who has had long experience
with this parasite, has stated : " Presumably the parasite would
eventually kill the host, if the oyster did not die of old age or something
else first, but this has not yet been proved."
The effects of B. cuculus in the growth of oysters as reported by
Menzel and Hopkins (1955a,b) have been reviewed in Chapter 4,
Section 11, A, 5.
3. Bucephalus sp. (Fig. 115)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Az ygiata;
superfamily Bucephaloidea; family Bucephalidae)
During a survey of zooparasites of Crassostrea virginica in Rhode
Island, U.S.A., we (Cheng and Burton, 1965b; Cheng, 1965c) found
the long dendritic sporocysts of a species of Bucephalus in oysters
from Ninigret Pond in Washington County. The cercariae produced
within these sporocysts are very similar to those of B. cuculus but two
distinct differences between this form and 3. cuculus are evident.
Firstly, the primary site of infection by the Rhode Island form is the
digestive gland rather than the gonads. Secondly, the growing terminal
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
pointed out that a t least some of the trematodes which Tennent believed
to be B. cuculus metacercariae and adults could have been those of a
species of Rhipidocotyle. It should be pointed out, however, that
Tennent (1909) did prove that eggs or miracidia from an unknown
adult bucephalid in the gar, Lepasdosteus osseus, could infect Crassostrea
virginica and develop into sporocysts which grow for a t least one month.
However, whether this parasite of the gar is B. cuculus is not known.
Ecology. According to Hopkins (1954a), B. cuculus, from what is
known, occurs in oysters from New Jersey to Texas, but its distribution
is not continuous throughout this range. It is also known that the
incidence of infection in Crassostrea virginica is highest in small
landlocked estuaries.
Physiology. Nothing is known about the physiology of 3. cuculus
except that it apparently cannot survive high salinities.
Pathology.
A detailed histopathological study of Crassostrea
virginica parasitized by B. cuculus has not yet been made although
certain pathological changes are known. It is known that B. cuculus
sporocysts utilize the oyster's gonads as the primary site of infection,
and in so doing usually cause parasitic castration. As the sporocysts
increase in length and undergo further branching, practically all of
the organs of its host, except the foot, become infiltrated. Whether
the parasite will eventually kill the oyster has not been studied under
controlled conditions. Hopkins (1957a), who has had long experience
with this parasite, has stated : " Presumably the parasite would
eventually kill the host, if the oyster did not die of old age or something
else first, but this has not yet been proved."
The effects of B. cuculus in the growth of oysters as reported by
Menzel and Hopkins (1955a,b) have been reviewed in Chapter 4,
Section 11, A, 5.
3. Bucephalus sp. (Fig. 115)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Az ygiata;
superfamily Bucephaloidea; family Bucephalidae)
During a survey of zooparasites of Crassostrea virginica in Rhode
Island, U.S.A., we (Cheng and Burton, 1965b; Cheng, 1965c) found
the long dendritic sporocysts of a species of Bucephalus in oysters
from Ninigret Pond in Washington County. The cercariae produced
within these sporocysts are very similar to those of B. cuculus but two
distinct differences between this form and 3. cuculus are evident.
Firstly, the primary site of infection by the Rhode Island form is the
digestive gland rather than the gonads. Secondly, the growing terminal