Rhabdocoels of the genus Paravortex are parasites of marine
molluscs. The bent-nosed clams, Macoma nasuta(Conrad, 1837) of
Yaquina Bay, Lincoln County, Oregon are commonly infected with a new
species of Paravortex. The morphology of the adult worm has been
described and it has been compared to the other three species of
this genus.
The percent infection increased as the size of the clams
increased. Analysis of the size frequency distribution of the clam
population suggests at least two age classes. Incidence of infection
was substantially lower in the younger of these two classes. Clams
less than 14 mm in length were not infected. Possible reasons for
this distribution of the parasite population were discussed.
A peak in the percent of infection, in the incidence of
multiple infection, and in the abundance of immature worms was
found during April, May, and June, 1968. These data suggest a seasonal
periodicity in the reproduction of Paravortex sp. nov.
A correlation between the sex of the bent-nosed clams and
the incidence and degree of infection could not be established.
Paravortex sp. nov. was found only in the pericardial cavity
of Macoma nasuta. It is postulated that the rhabdocoel enters this
cavity from the suprabranchial space by passing through the kidney.
Possible methods by which this endoparasitic rhabdocoel obtains food
were discussed.
Physical damage to the host clam could not be shown to be the
result of parasitic infections. Multiple infections of as many as
28 worms did not appear to physically impair the clam.
Observations of the morphology and behavior of living worms
were made and conclusions were reached concerning the nature of the
symbiotic relationship between Paravortex sp. nov. and its host.
Examination of collections of Macoma nasuta made in Coos Bay,
Oregon, and Puget Sound, Washington,produced no rhabdocoels. / Graduation date: 1970
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37322 |
| Date | 11 December 1969 |
| Creators | Hanson, Alfred Warren |
| Contributors | Pratt, Ivan |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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