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About the Mollusk Collection

The collection of the Mollusk Division at The Ohio State University Museum Of Biological Diversity comprises >1.5 million dry and >110,000 fluid-preserved molluscan  specimens in ~120,000 cataloged lots (of which ~27,000 are fluid-preserved). At least 100,000 lots worth of high-quality backlog (identified, with good locality data) are estimated to be present in the collection. Catalogued lots from the Mollusk Collection are cited in the literature using the prefix “OSUM”. 

A recent paper by Sierwald et al. (2017) shows that we have the 13th largest collection of mollusks in North America by number of lots, and that our collection quadrupled in size in the period between 1975 and 2017, making us the second fastest-growing mollusk collection in the country over the last half century. 

Though the Division exists mainly to maintain, grow, and provide access to our collections, we have a long history of deploying taxonomic knowledge in the service of local and international conservation efforts, and we continue this work through our ongoing collaborations with the Ohio Department of Natural Resources (ODNR) Division of Wildlife and the Columbus Zoo and Aquarium. These organizations are the principal partners with whom we run the Freshwater Mussel Conservation and Research Center (FMCRC). You can read more about our work with ODNR and the zoo here.


The bivalve collection contains ~86,000 catalogued lots, 99% of which are from the US and Canada. 96% of the lots are species of the family Unionidae (freshwater mussels). It is the largest collection of freshwater bivalves in the world by volume, number of specimens, and number of lots.


The gastropod collection, catalogued separately and stored in a neighboring room, is smaller, though more diverse taxonomically and geographically. It contains ~32,000 lots of land, freshwater, and marine snails from around the world, and boasts the 3rd largest collection of North American pleurocerid snails in the world.

Types, Vouchers, and Historic Collections

The division has relatively few type specimens (<20 primary and <200 secondary types), but does serve as an important repository for tens of thousands of voucher specimens cited in the scientific literature and government reports. There are historically important collections from early American freshwater malacologists such as Henry Moores, Samuel P. Hildreth, William Holden, Isaac and Thomas Lea, Timothy Abbott Conrad, James Lewis, and others. See this page for details on historical collections present in the Mollusk Division.

Geographic and taxonomic Strengths

The main strength of the collection are its large lots of rare, extinct, and endangered species native to the United States, particularly unionid bivalves and pleurocerid snails from the Midwest (Ohio, Wisconsin, Indiana, Illinois) and southeast (Kentucky, Tennessee, West Virginia, Alabama), which are both global biodiversity hotspots of freshwater species. Secondary strengths are our large proportion of fluid preserved lots, detailed ecological and locality data, and meticulous physical curation. These strengths reflect the research interests and lifelong collecting efforts of the previous curators Drs. David H. Stansbery, Carol B. Stein, and G. Thomas Watters.