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Physella lordi (Baird, 1863)
Twisted Physa
Family: Physidae


© Ian Gardiner     (Photo ID #95926)


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Distribution of Physella lordi in British Columbia in British Columbia

Species Information

This family of snails is characterized by shells exhibiting sinistral or left-handed coiling They are typically elliptical to ovate in shape with a large ovate aperture and a short spire (Perez et al. 2004). They display a lot of ecophenotypic variation and are difficult to identify (Perez et al. 2004).


Like other physids, this species is ectothermic and cannot regulate its body temperature, and as such, prefers habitat with favourable tempratures for reproduction. As with other members of this snail family, this is an egg-laying hermaphroditic species that lays eggs in the spring; eggs hatch directly as substrate-dependent juveniles.


“Known localities are all large or medium sized oligotrophic lakes (Taylor, 2003)” (BCCDC 2010).


Global Distribution

In North America, this species is reported from British Columbia and Washington (Taylor 2003).
Distribution in British Columbia

In British Columbia, this species is reported from Kootenay, New Westminster, Yale districts, and Lake Osoyoos (Taylor 2003).

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeS4S5YellowNot Listed

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

Synonyms and Alternate Names

Physa lordi Baird, 1863
Physa zomos Baily & Baily, 1952

Additional Range and Status Information Links

Species References

British Columbia Ministry of Environment, Lands and Parks. 2000. Freshwater molluscs. BC Ministry of Environment, Lands and Parks, Victoria.

British Columbia Conservation Data Centre. 2010. BC Species and Ecosystem Explorer. Species Report. BC Ministry of Environment, Victoria. Available online.

Perez, Kathryn, E., Stephanie A. Clark and Chafles Lydeard (eds). 2004. Showing Your Shells. A Primer to Freshwater Gastropod Identification. University of Alabama. Available online.

General References