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These species might be called "bait fishermen".  The eggs cohere in groups, called conglutinates, that are released into the water to be fed upon by the host fish.  When the conglutinate is bitten, glochidia are dislodged from the eggs and attach to the host's gills.  In addition to the fertile eggs bearing glochidia, the conglutinates of Fusconaia and certain other species also include a large number of sterile eggs that do not contain glochidia.  The sterile eggs are often brightly colored and relatively opaque.  They appear to serve to make the conglutinate more visible and perhaps also more palatable to the host fish.  Individual mussels produce either red or white conglutinates.

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Female ebonyshell with conglutinates.  Collected by John Harris. White River, Arkansas. These ebonyshell conglutinates are approximately 2 cm long. Fertile eggs with glochidia are transparent- sterile eggs are pink (ebonyshell).
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Higher magnification of fertile and sterile eggs (ebonyshell: F\usconaia ebena). Immature red and white conglutinates of Ozark shell (Fusconaia ozarkensis). Embryos are smaller & darker than sterile eggs. Mature red and white conglutinates of Wabash pigtoe (Fusconaia flava).

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