The Atlantic drainages of Georgia, comprising approximately 40% of the waters of the state, are presently covered... ›› more
The four ecoregions of North Carolina drain toward the Atlantic through six major river systems... ›› more
Although perhaps not as environmentally heterogeneous as neighboring states, South Carolina does include... ›› more
The survey reported here is focused on the eastern 75% of the state, draining from the Blue Ridge to the Atlantic... ›› more
All waters draining into the Tennessee River above the Alabama line, including SW Virginia, W North Carolina, and N Georgia... ›› more
A study area of approximately 150,000 km2, including Delaware, Maryland, New Jersey, eastern Pennsylvania and the West Virginia panhandle... ›› more
A survey of all waters draining into the Ohio River upstream from the mouth of the Tennessee/Cumberland at River Mile 920... ›› more
> Habitat & Distribution
The range of G. crista
is holarctic, across northern latitudes worldwide. Here in
North
America populations inhabit the range of rich, lentic habitats, from
eutrophic lakes to temporary ponds, extending from Ontario to the
Northwest Territories and Alaska, and from Maine to Minnesota (Clarke
1981). In Norway, Økland (1990) categorized G. crista
as a “pond species.” The population inhabiting Poland’s
Mikolajskie Lake appeared positively associated with macrophytes
(Soszka 1975).
Although not uncommon in Canada (Prescott & Curteanu, 2004),
populations of G. crista
are rare in the U.S. Great Plains. We are aware of previous
records from a single site in South Dakota (Over 1915), a single site
in north-central Nebraska (Taylor 1960), two sites in Wyoming (Beetle
1989) and from four temporary habitats in North Dakota (Cvancara,
1983). We ourselves have documented five populations of G. crista in our
four-state Great Plains study area, inhabiting the backwaters of rivers
and creeks in glaciated regions of North Dakota.
> Ecology & Life History
Dillon
(2000: 138 – 140)
conducted a survey of the relationship between adult size and newborn
size in freshwater gastropods across approximately 55 reference works,
74 populations, ultimately discovering that G. crista has both
the smallest adult size and the smallest hatchling size among the
Pulmonata.
One
or two eggs are deposited per capsule, twice to thrice a year
(Richardot-Coulet and Alfaro-Tijera, 1985; Jokinen, 1992).
Adults
overwinter and disappear after oviposition in the spring
(Richardot-Coulet and Alfaro-Tijera, 1985). This is life
cycle
type D(iis)
of Dillon (2000:156 – 162).
> Taxonomy & Systematics
The species we identify here as Gyraulus crista was
initially described in the genus Nautilus
by Linneaus in 1758. It was subsequently placed in Planorbis by O. F.
Müller (1773), and then split out to Armiger by Hartmann
(1843). Both Baker (1945) and Hubendick (1955) preserved Armiger at the
genus level, but the taxon was ultimately subsumed under Gyraulus by
Meier-Brook (1983).
Populations of G. crista
can demonstrate substantial variation in the prominence of shell ridges
(Clarke 1973, Cvancara 1983). Reduction of ridges has been
correlated with substrate type, especially decaying Typha cattails
(Spyra and Strzelec, 2013).
> Maps and Supplementary Resources
> Essays
- See my post to the FWGNA blog of 11Apr08 for a review of the Classification of the Planorbidae.
- Or view the (Hubendick 1955) classification of North American planorbids in a tabular format [here].
> References
Baker, F. (1928) Freshwater
Mollusca of Wisconsin, Part I, Gastropoda. Bull. Wisc. Geol. Natur.
Hist. Survey, no. 70. University of Wisconsin Press, Madison.
Baker, F. (1945)
The Molluscan Family Planorbidae. Urbana: University of Illinois
Press.
Baker, H. B. (1946)
Index to F.C. Baker's "The Molluscan Family Planorbidae." Nautilus, 59,
127-41.
Burch, J.B. (1989)
North American Freshwater Snails. Malacological Publications, Hamburg,
Michigan.
Clarke, A.H. (1979) Gastropods as indicators of trophic
lake stages. Nautilus 93:138-142.
Clarke, A.H.
(1981)
The Freshwater Molluscs of Canada. National Museum of Natural Sciences,
National Museums of Canada, Ottawa, Canada.
Dillon, R.T., Jr. (2000)
The Ecology of Freshwater Molluscs. Cambridge University Press,
Cambridge, United Kingdom.
Hubendick, B.
(1955) Phylogeny in the Planorbidae.
Trans. Zool. Soc. London 28: 453-542.
Jokinen, E.H. (1992)
The
freshwater snails of New York State. New York State Museum Biological
Survey, New York State Museum Bulletin 482.
Meier-Brook, C. 1983.
Taxonomic studies on Gyraulus
(Gastropoda: Planorbidae). Malacologia 24: 1 - 113.
Økland, J. (1990)
Lakes and Snails. Oegstgeest, Netherlands. W.
Backhuys.
Prescott, D.R.C., and
Curteanu, M.M. 2004.
Survey of Aquatic Gastropods in the Central Parkland Subregion of
Alberta. Edmonton, AB: Alberta Sustainable Resource Development, Fish
and Wildlife Division, Alberta Species at Risk Report No.92.
Richardot-Coulet, M.L.
and Alfaro-Tijera, L. 1985. The life cycle and ecology of
the freshwater Planorbidae Armiger
crista L. Journal of Molluscan Studies 51: 31–51.
Soszka, G. (1975) The invertebrates on submerged macrophytes in three
Masurian lakes. Ekol. Pol. 23: 371 – 391.