FWGNA > Species Accounts > Physidae > Physa acuta
Physa acuta Draparnaud 1805
“Physella heterostropha” 
  • click to view larger

> Habitat & Distribution

Physa acuta is the most common and widespread freshwater gastropod inhabiting our entire 14-state study area, a title it could probably claim for North America, and quite possibly the world (Dillon et al., 2002).  Populations may inhabit any and all freshwaters whatsoever from the equator to boreal latitudes, but reach maximum densities in lentic environments, especially those that are rich, disturbed and/or artificially eutrophic.  FWGNA incidence rank I-5.

> Ecology & Life History

Physa acuta is a “weedy” or R-selected species, in the sense of Dillon (2000: 131-135). Its rapid maturation, high reproductive rate, and ease of culture have made it the “fruit fly of malacology,” spawning scores of detailed studies on life history (Clampitt 1970), behavior (McCarthy & Fisher 2000), competition (Kesler et al.1986), parasitism (Ebbs et al. 2018) and predation (Crowl & Covich 1990, Alexander & Covich 1991, DeWitt et al. 1999, 2000).

Jokinen’s (1987) analysis of the distribution of P. acuta in Connecticut and New York (listed as P. heterostropha) led her to classify it as a “C-D tramp,” potentially present in nearly every community.  Dillon’s (2000: 360-363) reanalysis of these data suggested that P. acuta populations in Connecticut seem to be Undifferentiated with respect to life history adaptation.

Laboratory populations mature in 6 – 8 weeks, male function arriving slightly before female function, each adult laying 50 – 100 eggs weekly thereafter for up to a year (Wethington & Dillon 1993). They prefer to outcross, and can store allosperm for very long periods of time (Wethington & Dillon 1991, 1997).  But they self-fertilize successfully in isolation, and low levels of self-fertilization even seem to take place in females with proven allosperm reserves (Dillon et al. 2005a).  See Wethington & Dillon (1996) for a review of mating behavior.  If, after reading all the Dillon & Wethington references cited below, some question still remains in your mind regarding any aspect of the reproductive biology of P. acuta, please notify me and I will attend to it immediately, indeed.

> Taxonomy & Systematics

A variety of genetic and molecular phylogenetic studies have included samples of P. acuta worldwide (Wethington et al., 2009; Bousset et al. 2014, Dillon 2018, Ebbs et al. 2018).  Junior synonyms include heterostropha (Say 1817), integra (Haldeman 1841), virgata (Gould 1855), cubensis (Pfeiffer 1839), and many others (Dillon et al. 2002, 2005b, Wethington & Lydeard 2007, Wethington et al. 2009).

Until recently it was believed that the North American Physidae numbered more than 40 species, and a variety of elaborate classification schemes have been proposed (eg, Te 1978, 1980).  All of the physids common in the southeastern U.S. have at times been referred to the genus Physella.  It is now clear that most of this nominal diversity is attributable to phenotypic plasticity (Auld & Relyea 2011, Gustafson et al. 2014, but see Dillon & Jacquemin 2015) and that the true number of American species is closer to ten (Wethington 2004a, Wethington & Lydeard 2007).  The simple two-genus system favored by earlier workers (Walker 1918) would seem sufficient, all species of the American southeast referable to the genus Physa.  See my essay of 12Oct07 below for more regarding the classification of the Physidae.

> Supplementary Resources [PDF]


  • Physa acuta stars in a YouTube video, with special thanks to Bobby Martin of Martin Microscopes!

> Essays

> References

Alexander, J., and A. Covich (1991)  Predator avoidance by the freshwater snail Physella
virgata in response to the crayfish Procambarus simulans.  Oecologia 87:435-442. 
Auld J., and R. Relyea (2011)  Adaptive plasticity in predator-induced defenses in a common freshwater snail: altered selection and mode of predation due to prey phenotype. Evolutionary Ecology 25: 189-202.
Bousset, L., P-Y. Henry, P. Sourrouille, & P. Jarne (2004)  Population biology of the invasive freshwater snail Physa acuta approached through genetic markers, ecological characterization and demography. Molec. Ecol., 13: 2023-2036.
Bousset, L., J-P. Pointier, P. David, and P. Jarne (2014) Neither variation loss, nor change in selfing rate is associated with the worldwide invasion of Physa acuta from its native North America. Biological Invasions 16: 1769-1783.
Buth, D. G., and J. J. Suloway (1983) Biochemical genetics of the snail genus Physa:  A comparison of populations of two species. Malacologia 23:351-359. 
Clampitt, P. T. (1970) Comparative ecology of the snails Physa gyrina and Physa integra. Malacologia 10:113-151.
Clampitt, P. T.  (1974)  Seasonal migratory cycle and related movements of the freshwater pulmonate snail, Physa integra.  Amer. Midl. Natur. 92: 275-300.
Crowl, T., and A. Covich (1990) Predator-induced life-history shifts in a freshwater snail. Science 247:949-951. 
Dawson, J. (1911) The biology of Physa:  in J. B. Watson ed. Behavior Monographs. 1(4):1-120. 
DeWitt, T. J., A. Sih, & J. Hucko (1999) Trait compensation and cospecialization in a freshwater snail:  size, shape, and antipredator behaviour.  Anim. Behav. 58:397-407. 
DeWitt, T. J., B. W. Robinson, & D. S. Wilson (2000) Functional diversity among predators of a freshwater snail imposes an adaptive trade-off for shell morphology. Evolutionary Ecology Research 2:129-148. 
Dillon, R. T., Jr. (2000) The Ecology of Freshwater Molluscs.  Cambridge University Press, United Kingdom. 509 pp. 
Dillon, R. T., Jr. (2018)  Volatility in the effective size of a freshwater gastropod population.  Ecology and Evolution 8: 2746 - 2751. [PDF]
Dillon, R. T., Jr., and K. Davis (1991) The diatoms ingested by freshwater snails:  Temporal, spatial, and interspecific variation. Hydrobiologia 210:233-242.  
Dillon, R. T., Jr., C. E. Earnhardt & T. P. Smith (2004)  Reproductive isolation between Physa acuta and Physa gyrina in joint culture.  Am. Malac. Bull. 19: 63-68.
Dillon, R. T., Jr. and S. J. Jacquemin (2015)  The heritability of shell morphometrics in the freshwater pulmonate gastropod Physa.  PLoS ONE 10(4) e0121962.  [PDF]
Dillon, R. T., Jr., T. E. McCullough and C. E. Earnhardt (2005a)  Estimates of natural allosperm storage capacity and self-fertilization rate in the hermaphroditic freshwater pulmonate snail, Physa acuta. Invert. Repro. Devel. 47: 111-115.  [PDF]
Dillon, R. T. , Jr., J. D. Robinson, T. P. Smith & A. R. Wethington (2005b) No reproductive isolation between freshwater pulmonate snails Physa virgata and P. acuta. Southwest. Nat. 50: 415 - 422. [PDF]
Dillon, R. T., J. D. Robinson, and A. R. Wethington (2007)  Empirical estimates of reproductive isolation between the freshwater pulmonates Physa acuta, P. pomilia, and P. hendersoni.  Malacologia 49: 283-292.  [PDF]
Dillon, R. T., Jr., and A. R. Wethington (1994) Inheritance at five loci in the freshwater snail, Physa heterostropha. Biochem. Genet. 32(3/4): 75-82.  
Dillon, R. T., Jr., and A. R. Wethington (1995) The biogeography of sea islands: clues from the population genetics of the freshwater snail, Physa heterostropha. Syst. Biol. 44: 400-408.  [PDF]
Dillon, R. T., and A. R. Wethington (2006)  The Michigan Physidae revisited: A population genetic study.  Malacologia 48: 133 - 142. [PDF]
Dillon, R. T., A. R. Wethington, and C. Lydeard (2011)  The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa.  BMC Evolutionary Biology 11:144. [PDF] [html]  
Dillon, R. T., Jr., A. R. Wethington, J. M. Rhett, and T. P. Smith (2002) Populations of the European freshwater pulmonate Physa acuta are not reproductively isolated from American Physa heterostropha or Physa integra.  Invert. Biol. 121(3):226-234. [PDF]
Ebbs, E. T., E. S. Loker and S. V. Brant (2018)  Phylogeny and genetics of the globally invasive snail Physa acuta Draparnaud 1805, and its potential to serve as an intermediate host to larval digenetic trematodes.  BMC Evolutionary Biology 18: 103.
Gustafson, K. D., B. Kensinger, M. Bolek, and B. Luttbeg (2014) Distinct snail (Physa) morphotypes from different habitats converge in shell shape and size under common garden conditions. Evolutionary Ecology Research 16: 77–89.
Janicke, T., P. David, and E. Chapuis (2015)  Environment-dependent sexual selection: Bateman's parameters under varying levels of food availability.  American Naturalist 185: 756-768.
Janicke, T., N. Vellnow, T. Lamy, E. Chapuis, and P. David (2014)  Inbreeding depression of mating behavior and its reproductive consequesnces in a freshwater snail. Behavioral Ecology 25: 288 - 299.
Janicke, T., N. Vellnow, V. Sarda and P. David (2013)  Sex-specific inbreeding depresssion depends on the strength of male-male competition.  Evolution 67: 2861-2875.
Jarne, P., M-A Perdieu, A-F Pernot, B. Delay, and P. David (2000)  The influence of self-fertilization and grouping on fitness attributes in the freshwater snail Physa acuta: population and individual inbreeding depression. J. Evol. Biol. 13:645-655. 
Kesler, D. H., E. H. Jokinen, and W. R. Mumms (1986) Trophic preferences and feeding morphology of two pulmonate snails species from a small New England pond, U.S.A. Can. J. Zool. 64:2570-2575. 
McCarthy, T., and W. Fisher (2000) Multiple predator-avoidance behaviours of the freshwater snail Physella heterostropha pomilia: responses vary with risk. Freshw. Biol. 44:387-397. 
Te, G. A. (1975)  Michigan Physidae, with systematic notes on Physella and Physodon (Basommatophora:  Pulmonata). Malacological Review 8(1-2):7-30. 
Te, G. A. (1978) The systematics of the family Physidae (Basommatophora:  Pulmonata). Ph.D. Dissertation, University of Michigan, pp. 325. 
Te, G. A. (1980) New classification for the family Physidae (Pulmonata:  Basommatophora). Arch. Moll. 110:179-184.
Turner, A. M. & S. L. Montgomery.  2009.
 Hydroperiod, predators and the distribution of physid snails across the freshwater habitat gradient.  Freshwater Biology 54: 1189-1201.
Wethington, A. R. (2004a) Phylogeny, taxonomy, and evolution of reproductive isolation in Physa (Pulmonata: Physidae)  Ph.D. dissertation, University of Alabama, Tuscaloosa.
Wethington, A. R. (2004b)  Family Physidae. A supplement to the workbook accompanying the FMCS Freshwater Identification Workshop, University of Alabama, Tuscaloosa. 24 pp. [PDF]
Wethington, A. R. and R. T. Dillon, Jr. (1991)
  Sperm storage and evidence for multiple insemination in a natural population of the freshwater snail, Physa. Am. Malac. Bull. 9:99-102.
Wethington, A. R. and R. T. Dillon, Jr. (1993)
Reproductive development in the hermaphroditic freshwater snail, Physa, monitored with complementing albino lines. Proc. Royal Soc. Lond. B 252:109-114. [PDF]
Wethington, A. R. and R. T. Dillon, Jr. (1996) Gender choice and gender conflict in a non-reciprocally mating simultaneous hermaphrodite, the freshwater snail, Physa.  Anim. Behav. 51:1107-1118. [PDF]
Wethington, A. R. and R. T. Dillon, Jr. (1997)  Selfing, outcrossing, and mixed mating in the freshwater snail Physa heterostropha:  lifetime fitness and inbreeding depression. Invert. Biol. 116(3):192-199.   [PDF]
Wethington, A.R. E.R. Eastman, & R. T. Dillon, Jr. (2000)  No premating reproductive isolation among populations of a simultaneous hermaphrodite, the freshwater snail Physa. In: Freshwater Mollusk Symposia Proceedings. Tankersley, RA, Warmolts DI, Watters GT, Armitage BJ, Johnson PD & Butler RS, eds. pp. 245 – 251. Ohio Biological Survey, Columbus.   
Wethington, A. R. & C. Lydeard (2007)  A molecular phylogeny of Physidae (Gastropoda: Basommatophora) based on mitochondrial DNA sequences.  J. Molluscan Stud. 73: 241 - 257. [PDF]
Wethington, A.R., J. Wise & R. T. Dillon, Jr. (2009)  Genetic and morphological characterization of the Physidae of South Carolina, with description of a new species.  Nautilus 123: 282-292.  [PDF]