Utterbachia imbecilis
River Mussel Family (Unionidae)

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The Paper Pondshell is a short-lived species that can grow to about 4 inches (100 mm). It has an elongate and inflated shell that is very thin and delicate. It is rounded on one end and bluntly pointed on the other. The interior is white and the exterior is smooth and glossy in colors tan, green or brown.

Widely distributed throughout eastern US and southeastern Canada. It is common in Nebraska in rivers, ponds and reservoirs. The specimen shown here was found in the Great Marsh during low water in 2022.

The Paper Pondshell is a filter feeder that removes food particles from the water, primarily phytoplankton (algae). Sexes are separate. Males release sperm into the water and females take in the sperm while filtering. Females remain gravid from several weeks to several months. The larvae, called glochidia, are parasitic on the gills of fish. They attach to gills to facilitate distribution to other areas and drop off to complete development.

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