THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands |
Identify taxa MolluscaUnionoidaAnodontaAnodonta oregonensis |
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  Anodonta oregonensis (Oregon floater)
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| This species originally could be found from California to Alaska, and east to Nevada and Utah. However, its taxonomic standing has long been in question, so its historic range is unclear. Recent collections have been made in the Willamette and Columbia Rivers. The Oregon Floater prefers low gradient and low elevation rivers, lakes and reservoirs, and often shares habitat with the California Floater. The Coho Salmon serves as a host for immature Oregon Floaters. This species has likely been adversely affected by the same factors as other Anodonta species: water diversion, competition with non-natives and pollution. | Size: xlarge Identifying feature(s): the posterior part of the shell is not dramatically higher than the anterior part; the shell is rounded on the ventral (opposite the hinge) margin; it is swollen most in the middle, below the umbo, not just along the posterior ridge. Habitat: soft-bottomed rivers, reservoirs and lakes Tolerance: moderate |
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