Lackawanna River Corridor Association

Lackawanna River Pouch Snails, Limpets, & Fingernail Clams
Pouch snails, limpets, and clams are known as Mollusks. They are divided into two classes, Gastropoda (snails and limpets) and Bivalvia (clams).
Class: Gastropoda
Key features
single shell covering
presence of a fleshy "foot"
size range: snails, up to 1/4";limpets, up to 1/16"

  Pouch snails and limpets feed by scraping algae and bacteria from stones, leaves, and other substrates. They are considered to be pollution tolerant organisms and are primarily found within lower reaches of the River, downstream of Scranton. Pouch snails are fairly common within this reach and can often be observed "grazing" on the top of stones. Limpets are not as common.

Family: Physidae
Genus: Physella (pouch snail)
Family: Ancylidae
Genus: Ferrissia (limpet)

Class: Bivalvia
Key features:
2 hinged shells
size range: up to 1/8"

  All freshwater clams are filter feeders, which means they feed on small plant particles and bacteria suspended in the water column. The clams found in the River are quite small and are known as finger-nail clams. They are pollution intermediate organisms which have primarily been found from Forest City upstream and within lower reaches, downstream of Taylor. They are not common and are very rarely found in the Mid Valley or Scranton area.

Class: Bivalvia
Family: Sphaeriidae
Genus: Pisidium (finger-nail clam)