Pyramidellid Snails of Oysters


Category 4 (Negligible Regulatory Significance in Canada)

Common, generally accepted names of the organism or disease agent

Pyramidellid snails.

Scientific name or taxonomic affiliation

Boonea spp. and Odostomia spp. of the gastropod family Pyramidellidae.

Geographic distribution

Ubiquitous but most ectoparasitic species have been reported from the North Atlantic Ocean.

Host species

Crassostrea virginica, Ostrea edulis and many species of mussel, clam, cockle and scallop.

Impact on the host

Pyramidellids normally occur close to the mantle edge on the shell of the host, where they penetrate the soft tissues using a stylet and proboscis and feed off the oyster tissue fluids. The oyster may form characteristic pockets in the shell margin in response to the presence of the snails indicating irritation to the oyster tissues. In the laboratory, Boonea impressa was capable of transmitting the oyster pathogen Perkinsus marinus between Crassostrea virginica (White et al. 1987). In the field (Gulf of Mexico, Texas, U.S.A.), about 10 B. impressa on each C. virginica was associated with reduced growth rate and increased intensity of Perkinsus marinus infections in the oysters over a four month exposure period (Wilson et al. 1988).

Diagnostic techniques

Gross Observations: Small white snails less than 3 mm long attached to the mantle margins of oysters.

Methods of control

No known methods of prevention or control. Recommend avoidance of introduction of infected oysters into areas where these snails have not been previously recorded.


Lauckner, G. 1983. Diseases of Mollusca: Bivalvia. In: O. Kinne (ed.) Diseases of Marine Animals. Volume II: Introduction, Bivalvia to Scaphopoda. Biologische Anstalt Helgoland, Hamburg, p. 797-800.

White, M.E., N.E. Powell, S.M. Ray and E.A. Wilson. 1987. Host-to-host transmission of Perkinsus marinus in oyster (Crassostrea virginica) populations by the ectoparasitic snail Boonea impressa (Pyramidellidae). Journal of Shellfish Research 6: 1-5.

Wilson, E.A., E.N. Powell and S.M. Ray. 1988. The effect of the ectoparasitic pyramidellid snail, Boonea impressa, on the growth and health of oysters, Crassostrea virginica, under field conditions. Fishery Bulletin 86: 553-566.

Citation Information

Bower, S.M. (2013): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Pyramidellid Snails of Oysters.

Date last revised: May 2013
Comments to Susan Bower

Date modified: