Lake Fingernail Clam
The lake fingernail clam is a widely-distributed bivalve of unknown origin.
About This Species
The shell of the lake fingernail clam is thin, up to 8 mm in length, round and slightly to highly inflated. The shell is light in color and somewhat triangular in shape or outline. The umbo is central and pronounced.
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Range
In the United States, the range of the lake fingernail clam includes the northern states to Alaska, across to Canada, mainly south of the treeline. It is considered threatened in the southern extent of its range, including New Mexico, Utah, and Virginia. This species inhabits high altitude lakes in Western Colorado and lower elevations in Eastern Colorado. It has been observed in the Arkansas, Colorado, Platte, Republican, Rio Grande, and San Juan River drainages and in the San Luis Valley.
The lake fingernail clam is also widespread throughout Europe, but it is considered rare in Syria and Turkey. In Asia it is found in the Palearctic northern portion, as well as the Arctic basin, Kamtchatka, northern China and Japan. More research is necessary to find the exact range in Eurasia.
The exact origin of this species is currently unknown, but its spread could be caused, at least in part, by birds. This species was introduced to southern Australia.
Habitat
The lake fingernail clam is found in small and large lakes and reservoirs, marshes, ditches, rivers, and streams. This species seems to prefer swamps, ponds, and marsh drains, or well-vegetated margins of rivers and canals. It is capable of surviving in hard or soft water and it is tolerant of moderately polluted water or stagnant, poorly oxygenated conditions, as well as areas subject to seasonal drying or drought. Due to its high tolerance, this may be the only bivalve present in poor environments. The lake fingernail clam lives on muddy substrate, often anoxic mud, and frequently in areas where dense vegetation occurs. It is usually found at the base of aquatic plant stems.
Reproduction
The lake fingernail clam carries broods most of the year. Individual offspring vary in size and age class.