Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (1.37 MB bytes)

Title: Adaptations to host infection and larval parasitism in Unionoida

Author: Barnhart, Christopher M.; Haag, Wendell R.; Roston, William N.;

Date: 2008

Source: The North American Benthological Society 2008, 27(2):370-394

Publication Series: Miscellaneous Publication

Description: Freshwater mussel larval parasitism of fish is unique among bivalves. The relationship is primarily phoretic rather than nutritive; only the smallest glochidia and the haustorial larva grow substantially while on the host. Growth of the smallest larvae suggests a lower functional size limit of -150 )um for the juvenile stage. Most Ambleminae, the most diverse North American clade, infect host gills by attracting feeding fish. Many species of Pleurobemini and some Lampsilini release conglutinates of eggs and larvae that resemble host food items. Many Lampsilini and a few Quadrulini use mantle modifications to attract host fish to the female. The mantle of some Quadrulini forms a posterior chamber that holds glochidia for immediate release in response to host fish. In many Lampsilini, mantle flap lures and a protrusible marsupium promote attack by the host fish and direct extraction of glochidia from the marsupium by the host. Host extraction of glochidia from the brooding female might have favored the evolution of long-term brooding in ampsilini because glochidia need not be released by the female to encounter the host. A remarkable derivative of the host extraction strategy evolved in Epioblasma, which catch fish between the valves and release glochidia directly to the trapped host before releasing it. Host specificity is a critical feature of the evolutionary diversification and conservation biology of Unionoida. As temporary parasites, mussels must primarily evade the innate immune responses of the host, rather than the adaptive (acquired) responses. Evolution of host specificity is associated with selective encounter of host taxa, either because of host attraction strategies or because of dominance of particular host species in the habitat. The intricate relationships between mussels and fish are easily disrupted and, thus, contribute to the imperilment of many mussel species, yet they also fascinate us and compel conservation efforts.

Keywords: Unionoida, parasitism, freshwater mussel, glochidia, innate immunity, host specificity

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • You may send email to to request a hard copy of this publication. (Please specify exactly which publication you are requesting and your mailing address.)



Barnhart, Christopher M.; Haag, Wendell R.; Roston, William N. 2008. Adaptations to host infection and larval parasitism in Unionoida. The North American Benthological Society 2008, 27(2):370-394


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.