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Yellow Lampmussel

Have you seen this animal?

It is Lampsilis cariosa, commonly known as the yellow lampmussel. The lampmussel is a species of freshwater mussel, a mollusk characterized by a two part or bivalve shell. The species was formerly widespread in the Connecticut River from Turners Falls downstream to the estuary. The only other southern New England population occurred in the Merrimack River, but that population became extinct by the early 20th century. The Connecticut River population has declined in this century as well but was still living in the main river until the 1950s. Until October of 1998, it had not been seen in the main-stem of the Connecticut River (see note below). During the 1980s, worn shells of dead animals were found with decreasing frequency and the last live animal seen was an adult male in the Holyoke power canals in 1984.

Then in the summer of 1996, a small group of young animals were found in the same power canals, one a young adult female.

The key characters of this Massachusetts and Connecticut endangered species are the bright yellow color without rays and the oval shape. Note on the live female the fleshy "flap" which is a feature of this species. If you see one of these animals, notify Doug Smith, Invertebrate Biologist, University of Massachusetts. Do not collect the animal as it is illegal to possess one. Photograph it instead and release it. We are collecting data to determine its status in the Connecticut River and other rivers to see if it can receive federal protection.

Note: On October 1, 1998 a diver found this young female lampmussel, as well as a number of shell fragments from larger specimens in the main-stem of the Connecticut River. The animal was living at a depth of 4 meters and was completely buried in the sand/gravel bottom with only the aperatures exposed. The surrounding area was heavily populated by Elliptio complanata, a common mussel in the river. This means that the Connecticut River population has not been extinguished and that rare populations of Lampsilis cariosa can still be found.


Fichtel, C. and D. G. Smith. 1995. The Freshwater Mussels of Vermont. Nongame and Natural Heritage Program, Vermont Fish and Wildlife Department, Technical Report 18, Leahy Press, Montpelier, VT.

Smith, D. G. 1995. Keys to the Freshwater Macroinvertebrates of Massachusetts (2nd edition). This manual can be purchased from the author.