264
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
nematodes in C. virginica collected in St. Mary’s Creek, St. Mary’s
County, Maryland. I n all instances, the nematodes were tightly coiled
in tissues in the region of the digestive diverticula (Fig. 172). When
observed in cross-section, each worm measures approximately 0.075 mm
in diameter. There appears to be little doubt that these are true
endoparasites ; however, the obligatory or facultative nature of their
association with oysters remains undetermined.
FIG. 172. Section of the oyster Grassostrea wirginica from Maryland showing cross- and
partial longitudinal sections of an unidentified nematode in Leydig tissue. Notice
leucocytosis in area surrounding nematode. (Section from which the photomicrograph was taken was kindly loaned by Mr. R. W. Burton, Rhode Island Fish and
Game Division.)
Another known instance of an unidentified nematode parasite of a
commercially important marine mollusc is the one encountered by
Vadel (1855) in the scallop Pecten (=Aequipecten). Vadel has given a
rather incomplete description of this nematode so that positive identification is not possible. He has merely stated that it was a larva,
3.5 cm long and 0.5 mm wide, tapering a t both ends but with a blunt
anterior and a pointed posterior extremity. A coiled punctate organ,
barely visible to the naked eye, is present near the anterior extremity.
When observed in the living state, this nematode executes a variety of
movements while rapidly coiling and uncoiling.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
nematodes in C. virginica collected in St. Mary’s Creek, St. Mary’s
County, Maryland. I n all instances, the nematodes were tightly coiled
in tissues in the region of the digestive diverticula (Fig. 172). When
observed in cross-section, each worm measures approximately 0.075 mm
in diameter. There appears to be little doubt that these are true
endoparasites ; however, the obligatory or facultative nature of their
association with oysters remains undetermined.
FIG. 172. Section of the oyster Grassostrea wirginica from Maryland showing cross- and
partial longitudinal sections of an unidentified nematode in Leydig tissue. Notice
leucocytosis in area surrounding nematode. (Section from which the photomicrograph was taken was kindly loaned by Mr. R. W. Burton, Rhode Island Fish and
Game Division.)
Another known instance of an unidentified nematode parasite of a
commercially important marine mollusc is the one encountered by
Vadel (1855) in the scallop Pecten (=Aequipecten). Vadel has given a
rather incomplete description of this nematode so that positive identification is not possible. He has merely stated that it was a larva,
3.5 cm long and 0.5 mm wide, tapering a t both ends but with a blunt
anterior and a pointed posterior extremity. A coiled punctate organ,
barely visible to the naked eye, is present near the anterior extremity.
When observed in the living state, this nematode executes a variety of
movements while rapidly coiling and uncoiling.