© 1996 by The Society for Integrative and Comparative Biology
Gill Structure in Zebra Mussels: Bacterial-Sized Particle Filtration1
Department of Zoology and Physiology Louisiana State University, Baton Rouge, Louisiana 70803
2Department of Microbiology Louisiana State University, Baton Rouge, Louisiana 70803
SYNOPSIS. The filtration mechanics of the gill of the zebra mussel, Dreissena polymorpha, allow this organism to capture particles less than 1 µm. The organization of gill cirri and the architecture of the cirri appear to be important in providing the organism with the ability to filter small particles. Bacteria may provide a useful nutrient source for these animals as bacterial proteins can be digested and assimilated into mussel proteins. Laboratory experiments indicate that D. polymorpha is capable of filtering and assimilating a wide range of bacteria ranging in size from 1–4 µm. Unionid species appear to be at least an order of magnitude less efficient at filtering bacteria than D. polymorpha. Because of its relatively smaller gill size, C. fluminea also filters bacteria less efficiently than D. polymorpha. We suggest that bacterial utilization by freshwater mussel species has important population and evolutionary implications.