Ramshorn Snail
Category
Native Gastropod (Family Planorbidae); pulmonate snail
Common Name
Ramshorn Snail
Species Name
Planorbidae (Family); no specific species
Distribution / Status (Tahoe)
Native to Tahoe region; found in quiet nearshore areas
Diagnostic Features
Flat planispiral shell; appears sinistral when viewed from above
Commonly Confused Species
New Zealand Mudsnail (Potamopyrgus antipodarum); Sinistral Pond Snail/Bladder Snail (Physidae)
Shell Shape / Form
Planispiral (flat-coiled, disk-like)
Shell Size
5–20 mm diameter
Shell Thickness
Thin, flattened
Aperture
Broad circular opening at shell margin
Shell Sculpture / Texture
Smooth, glossy
Color / Patterning
Red-brown to greenish, semi-translucent
Operculum covering aperture
Absent (pulmonated, can breathe air)
Soft Body Features
Flattened body; coiled intestine visible through shell; no operculum
Habitat Type
Calm, vegetated backwaters, ponds, and nearshore lake zones; tolerant of low oxygen and moderate nutrient enrichment
Substrate Preference
Submerged plants and organic debris
Depth Range
<2 m; attached to plants or detritus
Temperature Range
5–25 °C
Association / Behavior
Free-living; vegetation-associated. Glides on plant surfaces and detritus; occasionally floats upside down beneath the surface film using air trapped in shell.
Ecological Role / Impact
Native — oxygenates periphyton and recycles detritus; grazes on biofilm and decaying plants
Reproduction
Hermaphroditic; gelatinous egg masses on surfaces
Supporting Partners
The Martis Fund, a collaborative project of Martis Camp landowners, DMB/Highlands Group (the developers of Martis Camp), Mountain Area Preservation (MAP), and Sierra Watch. (See martisfund.org for more information)
The Community Impact Fund, Ashley Quinn Fund & the Foresight Fund held at the Tahoe Community Foundation
Additional thanks to the Tahoe Regional Planning Agency for providing specimens for studio filming
