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Fingernail clams, Sphaerium, Musculium, Pisidium sp.
Description: Fingernail clams are
tiny clams found throughout
Nebraska. There are a number of
species some of which can get up to 15-
20mm whereas others never get larger
than 4mm. As the name implies, the
largest ones are smaller than your
fingernail. Their shells are thin and
have true cardinal teeth that are
flanked by lateral teeth on both sides
(but you will need a microscope to see
them). Shells can be glossy or dull.
Nacre is always white or off-white
though some are so thin that you can
almost see through them.
Similar species: Asian clams have a
thick, heavy shell with coarse
concentric ridges.
Conservation status: None. We
don't track the status of Fingernail
clams.
Hosts: None. This species can
reproduce without a host.
Habitat: They are found in all types
of habitat from silty quiet streams to
fast water as well as ponds and lakes.
Some species can be found in
ephemeral ponds (ponds that often dry
up).
Distribution: Worldwide
Collection notes: I have found
Fingernail clams all across the state.
To date, I have tentatively identified
eleven species.
Comments: Fingernail clams are true
clams in that they do not need a fish
host to reproduce. Eggs are fertilized
internally and the young grow within
the shells of the adults, to be released
when they are self-supporting. They
filter minute food items out of the
water and, in turn, are food for many
organisms.
