Arctic Fingernailclam - Sphaerium nitidum
Fingernail clams are small "mostly about the size of a finger or thumbnail" bottom-dwelling, filter-feeders found in ponds, lakes and streams throughout Montana. They are native and can be quite abundant, providing food for a variety of animals and producing large accumulations of empty shells. These shells can be quite fragile compared to introduced Asian clams of the family Corbiculidae, which have not been reported in Montana, yet.
Shell small, less than 8 mm long; posterior end and dorsal margin rounded or forming an obtuse angle; striae maintain their spacing and height in the region of the beaks (La Rocque 1967).
Northern Canada south to the northern United States and in the Rocky Mountains south to Utah (Burch 1972).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
An arctic and alpine species that occurs in small and large lakes and in rivers of various widths, on diverse substrates (Clarke 1981).
Fingernail clams are mostly filter-feeders, siphoning in floating particulate organic materials ( small plant or animal) from the water column and straining out the particles and expel the strained water. Pedal feeding from the bottom with the foot muscle has also been observed.
It is a favorite food of arctic fish (Clarke 1981).
Up to 6 young, mostly of varying sizes, have been found in adult specimens (Clarke 1981).
- Literature Cited AboveLegend: View Online Publication
- Burch, J.B. 1972. Freshwater Sphaeriacean clams (Mollusca:Pelecypoda) of North America. EPA Biota of Freshwater Ecosystems Identification Manual No. 3. 31 pp.
- Clarke, A.H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa. 446 pp.
- La Rocque, A. 1967. Pleistocene Mollusca of Ohio. Department of Natural Resources, Division of Geological Survey Bulletin 62, Part 2. 113-365 + 8 plates.
- Additional ReferencesLegend: View Online Publication
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- Henderson, J. 1924. Mollusca of Colorado, Utah, Montana, Idaho, and Wyoming. University of Colorado Studies 13(2):65-223.
- Russell, R.H. and R.B. Brunson. 1967. A check-list of molluscs of Glacier National Park, Montana. Sterkiana 26:1-5.
- Additional Sources of Information Related to "Mussels / Clams"