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Pisidium compressum Prime, 1852
Ridgebeak Peaclam
Family: Sphaeriidae


© Ian Gardiner     (Photo ID #112719)


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Distribution of Pisidium compressum in British Columbia in British Columbia


Pisidium compressum is widespread in Canada and Alaska south of the tree line. It is found throughout the United States and extends into Mexico (Clarke, 1981). Next to P. casertanum, it is the most common sphaeriid in North America (Mackie, 2007). It is widespread in British Columbia.

This species is most common in lotic environments (creeks and rivers), although it is also common in shallow areas of small and large lakes. It inhabits only perennial water bodies, usually with some current or wave action (Mackie, 2007). It has a preference for sandy bottoms with vegetation, and shallow water (Herrington, 1962), though Clarke (1973) found this species associated with all types of bottom deposit, with mud the most frequent.

Note Author: Ian Gardiner

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeS5YellowNot Listed

BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Range and Status Information Links

Species References

Clarke, A.H. 1973. The freshwater molluscs of the Canadian Interior Basin. Malacologia 13 (1-2): 1-509.

Clarke, A.H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Ontario: 446pp.

Herrington, H.B. 1962. A revision of the Sphaeriidae of North America (Mollusca: Pelecypoda). Miscellaneous Publications, Museum of Zoology, University of Michigan, No. 118: 74pp, 7 plates.

Mackie, G.L. 2007. Biology of freshwater corbiculid and sphaeriid clams of North America. Ohio Biological Survey Bulletin New Series. Vol XV No. 3: ix + 436pp.